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2004 Local Authority studies
Analysis of data and evidence for
Tower Hamlets
Office for National Statistics, September 2004
Contents
Page
Executive summary 3
1 Introduction 4
2 Background information on Population Estimates and One Number Census 4
3 Analysis 5
3.1 Enumeration 5
a) Analysis of Council Tax data 6
b) Analysis of Enumerator Record Books (ERBs) 8
c) Analysis of Council Tax based response rates by 2001 Ward 8
d) Enumeration Information 9
e) Estimated response compared to other areas 9
f) Qualitative information obtained about the Census enumeration 10
3.2 Census Coverage Survey 10
a) Missing sample 10
b) Sample balance 10
Dummy form distribution 11
Recalculated Hard to Count score 13
c) Localised undercount and the CCS 17
d) CCS fieldwork and response rates 20
3.3 One Number Census process 20
a) Response rates 20
b) Collapsing in the ONC process 20
c) Outliers 21
d) Stratification 21
e) Household and person imputation results 24
4 Population definitions 24
5 Processing 25
6 Other - communal establishments 25
7 Other -administrative sources 25
8 Conclusions and recommendations 26
2
Executive summary
The Office for National Statistics (ONS) has now concluded a series of studies designed to improve
population estimates in the areas that proved to be hardest to count in the 2001 Census in England
and Wales. The results of this analysis, involving experts from local government and other bodies,
has confirmed the findings contained in reports by the Statistics Commission and the Local
Government Association. These reports concluded that the One Number Census (ONC) worked
well in most areas but that there were a few cases where it was not able to sufficiently adjust for
under-enumeration in exceptional circumstances.
More information can be found at www.statistics.gov.uk/pdfdir/census0704.pdf
A report was produced for each Local Authority examined, and this report sets out the analysis
and conclusions for the Local Authority of Tower Hamlets. It provides background information
about population estimates and the Census, and describes analysis carried out in certain key areas
- enumeration, Census Coverage Survey (CCS), One Number Census (ONC), population definitions
and processing. A comparison with administrative sources is also shown. Conclusions and
recommendations are detailed at the end of the analysis.
Tower Hamlets was selected for detailed analysis as part of the local authority population studies, as
it was identified as an area where there was a significant risk of an under-estimate of the population
by the 2001 Census.
This detailed analysis identified large differences between Census and Council Tax figures, however,
further analysis concluded that this was due to definitional differences.
Further analysis identified no significant problems with Census or CCS enumeration, no evidence of
localised under-enumeration and concluded that the assumptions made by the One Number Census
were appropriate for Tower Hamlets.
After consideration of all the evidence, it was decided that the current estimate remains the best
estimate of the population of Tower Hamlets in 2001, and therefore no adjustment has been made.
3
2004 Local Authority studies:
Analysis of data and evidence for Tower Hamlets
1 Introduction Table 2.1
Tower Hamlets (Census 2001 population Mid Year Estimate (MYE) series and revi-
196,106) is an area within Inner London, sions for 2000, 2001 and 2002
bordered in part by the River Thames. There
Population Change since 2000
are some characteristics of Tower Hamlets that MYE
make population enumeration and estimation 2000 MYE 186,700
difficult. There are blocks of flats with controlled Census 196,106 9,400
access, and also the area is home to some halls 2001 MYE 196,600 9,900
of residence for the University of North London
Revised 2001 MYE 201,600 14,900
and the City & Islington college.
Revised 2002 MYE 206,800 20,100
In order to estimate census undercount across
England and Wales contiguous Local Authorities
Tower Hamlets received an adjustment with
(LAs) were grouped together to form Estimation
the revised 2001 Mid-Year Estimates on 26/
Areas (EAs) which consisted of about half a
09/03. More information can be found at
million population. In most cases EAs consisted
www.statistics.gov.uk/about/Methodology_by_
of several Local Authorities. Where an LA was
theme/Revisions_to_Population_Estimates/
sufficiently large the EA consisted only of that
default.asp
one LA, i.e. the LA was an EA in itself. LAs were
divided into Enumeration Districts (EDs) which
Table 2.2 shows the Confidence Interval
were pre-planned workload areas of around
associated with the ONC population estimate.
200 households within which an individual
enumerator worked. EDs did not cross Ward
boundaries. Tower Hamlets is part of a Census Table 2.2
Estimation Area containing two other Local 95 per cent Confidence Interval for Tower
Authorities (LAs), Hackney and Islington. Hamlets One Number Census estimate
Tower Hamlets was selected for investigation for Relative C.I +/- Confidence Interval Range
a number of reasons: 3.9% 7,648 188,458 203,754
· The area had a large difference between
the Council Tax data and the Census
Mid Year Population Estimates
counts.
The following tables provide information on
· There were 10 outliers identified within Tower Hamlets’ population between 1991 and
the ONC process for the Local Authority, 2000. These indicate whether the population
which is a substantial number. has increased or decreased throughout the
· The area demonstrated the largest intercensal period, whether the area is one of
difference in its Hard to Count profile large change and what effect migration has had
between 1991 and 2001. on the area’s population.
2 Background information on Population
Estimates and One Number Census
Table 2.1 sets out the Census and mid year
estimates (MYEs) for Tower Hamlets for the
period 2000 – 2002. Note that the 2001 and
2002 mid year estimates shown here are those
based on 2001 Census data, while the 2000 mid
year estimate is based on rolled forward data
from the 1991 Census.
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www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Table 2.3
Population profile for the MYE series up to 2000 (unrevised)
Mid Year 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
Population Estimates 168.1 168.5 169.6 170.5 172.8 176.6 179.8 181.3 184.9 186.7
(Thousands)
NB: The mid-year population estimates in this table are those that existed before the 2001 Census,
and have since been revised.
Table 2.4
Average annual changes in components of population estimates (unrevised)
Average annual change since mid-91 E&W Tower Hamlets
(thousands)
Average annual change 0.5 2.1
Average annual natural change 0.3 1.8
Average annual change in migration 0.1 -0.7
NB: The numbers in the above table do not add up due to rounding.
Table 2.5
Migration profile for MYE series to 2000 (unrevised)
Migration Mid-92 Mid-93 Mid-94 Mid-95 Mid-96 Mid-97 Mid-98 Mid-99 Mid-00
Net Internal -2.5 -1.1 -1.6
Net International 0.8 0.9 1.0
Total Net -2.3 -1.6 -1.0 -0.5 1.0 0.4 -1.6 -0.1 -0.7
Table 2.5 shows that migration was variable White circles show postcodes with a Hard to
for Tower Hamlets over the intercensal decade Count (HtC) index of 1 (the easiest areas to
but generally demonstrated a trend of outward enumerate), light green circles have a HtC index
migration. The general trend of outward of 2 and dark green circles have a HtC index
migration is a contrast to the overall population of 3 (the hardest areas to enumerate). Local
change and in particular natural change, Authority boundaries are marked in blue and
shown in tables 2.3 and 2.4. This shows that the the Estimation Area boundary in red.
population in this area has grown rapidly, and
this is mainly due to large natural change. www.statistics.gov.uk/census2001/onc_qa/
pdfs/Tower_Hamlets.pdf
One Number Census Quality Assurance
information Information provided by the Local Authority
The One Number Census Quality Assurance Tower Hamlets Borough Council have not
Information Pack for Tower Hamlets, published queried their population estimates.
in 2003, can be found in the link below, and
includes the following information:
3 Analysis
· Population Estimates
This section of the report covers the detailed
· Confidence Intervals analysis carried out for Tower Hamlets. More
· Diagnostic Ranges information on the overall approach to the LA
studies can be found at www.statistics.gov.uk/
· Dependency Ratios downloads/theme_population/LAStudy_
· Age-Sex Profiles depicting the above FullReport.pdf
figures
3.1 Enumeration
· Census Coverage Survey Maps including
When looking at possible ward level undercount,
Hard to Count information
it is necessary to consider that one of the key
The map in the link below shows the location of assumptions underpinning the One Number
the CCS Postcodes within the Local Authority. Census (ONC) is that the undercount is
5
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
approximately randomly distributed - that is, The map shows that the ward shaded darkest blue
the distribution of the undercount is mainly (Bow East) is the one with the largest difference
determined by the age and sex profile of an between Census and Council Tax figures. The map
area and the distribution of hard to count areas also shows that this ward contains a number of
as measured by the hard to count index. The CCS postcodes. If the CCS has worked as it should,
assumption is that there are no other factors that undercount in this area will have been identified.
have a large influence, such as the quality of the Spitalfields and Banglatown ward has the second
work carried out by the census enumerators. If largest proportional difference but this is not
this assumption is not true the resulting ONC covered by any CCS postcodes so the undercount
estimates of population may not adequately reflect may not have been detected in this area. St
the true undercount. The Census Coverage Survey Katherines & Wapping was the other ward that
(CCS), although a large sample nationally, is highly had a large difference and this was covered by CCS
unlikely to be able to measure this additional postcodes. This should indicate that undercount
source of variability at low levels, i.e. Enumeration will have been identified. The performance of the
Districts or Wards. The Local Authority studies CCS in the Bow East ward and St Katherines &
have made detailed comparisons with Council Wapping is therefore investigated further in section
Tax data, and conducted in-depth analyses on 3.2 (c) - Localised undercount.
enumerator record books (ERBs). The findings of
these pieces of work are described below. The table below shows the differences between the
Census and Council Tax for each ward, ordered by
a) Analysis of Council Tax data percentage difference, so that the ward at the top
Tower Hamlets shows an overall difference between has the largest difference. As shown in Figure 3.1,
Council Tax records and the Census results of 3,367 there are three wards that have large differences
dwellings, a 4.2 per cent difference. This is the 8th between the Council Tax records and the Census
largest positive numerical difference, and the 7th database, these are Bow East, St Katherine’s and
largest positive proportional difference for the 376 Wapping and Spitalfields and Banglatown.
LAs in England and Wales.
The map on page 7 highlights the differences
between Council Tax and Census by ward. CCS
postcodes are indicated by the red dots.
Table 3.1.1
Differences between Census and Council Tax dwelling counts by 2003 ward
2003 Ward Census Dwellings Council Tax Dwellings Difference Percentage Difference
Bow East 4,259 5,072 813 19.1%
Spitalfields and Banglatown 2,991 3,315 324 10.9%
St Katherine’s and Wapping 5,554 6,056 502 9.0%
East India and Lansbury 4,475 4,741 266 5.9%
Bow West 4,435 4,698 263 5.9%
Millwall 6,160 6,457 297 4.8%
St Dunstan`s and Stepney 4,675 4,890 215 4.6%
Green
Limehouse 5,206 5,426 220 4.2%
Shadwell 4,492 4,670 178 4.0%
Blackwall and Cubitt Town 5,662 5,881 219 3.9%
Bethnal Green North 4,697 4,869 172 3.7%
Whitechapel 4,505 4,642 137 3.0%
Bromley-by-Bow 4,197 4,224 27 0.6%
Weavers 4,904 4,904 0 0.0%
Mile End and Globe Town 4,672 4,636 -36 -0.8%
Mile End East 4,268 4,223 -45 -1.1%
Bethnal Green South 5,080 4,895 -185 -3.6%
NB: Due to extensive boundary changes between Census day and 2003, most wards on the above table will be
different to 2001 wards. The more relevant changes are as follows
· Bow East was created from parts of Park and Bow wards
· St Katherine’s and Wapping was formed from parts of St Katherine’s and Shadwell.
· Spitalfield’s and Banglatown was made from part of the existing ward Spitalfield’s.
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www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Figure 3.1
Map showing the percentage difference between Council Tax and Census for Tower Hamlets
Bow East
Bethnal Green North Bow West
Mile End and Globe Town
Weavers
Bromley-by-Bow
Bethnal Green South
Mile End East
Spitalfields and Banglatown
St Dunstan`s and Stepney Green
East India and Lansbury
Whitechapel
Limehouse
Shadwell
St Katherine`s and Wapping
Blackwall and Cubitt Town
Millwall
Legend
CCS Postcodes
2% - 4%
0% - <2%
>0% - 2%
>2% - 4%
>4% - 6%
>6% - 8%
>8% - 10%
>10% - 12%
Census figures higher in pink areas.
19% - 20% Council Tax figures higher in blue areas.
7
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Difference between Census and Council Tax occupied and (and these are not all visitor households) which
unoccupied dwelling counts can also be considered as a type of dummy form
Tower Hamlets shows an overall difference (an ‘empty’ household).
between occupied dwellings according to the
Council Tax records and the Census results of - Many enumeration districts showed many more
79 dwellings, a -0.1 per cent difference. Amongst household forms in the ERBs than in the ED
all English LAs, this is the 322nd largest positive database.
numerical difference, and the equal 162nd
largest positive proportional difference. This The Park ward (which later became Bow
contrasts with the Council Tax differences East and Bow West) and St Katherine’s ward
above, indicating that the difference is mainly in contained a number of EDs with many more
unoccupied properties. household forms than in the ED database.
Spitalfields (which now makes up part of
Table 3.1.2 Spitalfields and Banglatown) did not show any
Differences between Census and Council large differences between the two sources for
Tax dwelling counts household forms. However it did contain some
Census CTB1 Difference % EDs that showed differences in the number
Difference of non-response dummy forms that were
Occupied 78,530 78,459 -79 0.1% completed.
Unoccupied/ 2,251 6,321 4,070 180.8%
Vacant
This would suggest that the enumeration was
poor in this area and that some households may
not have been correctly recorded. This may be
b) Analysis of Enumerator Record Books (ERBs) a cause for concern if the CCS did not work as
Investigations were carried out for Wards intended in this area.
where a high discrepancy in either direction
had been identified between the Census results c) Analysis of Council Tax based response rates by
and the Council Tax. This involved analysis of 2001 Ward
Enumerator Record Books (ERBs), investigating Table 3.1.3 shows a comparison of Council
individual records to assess the quality of the Tax Figures and households counted in the
enumeration in the area, to ensure that all Census, broken down by ward. An implied
addresses had been accounted for and establish Census response rate has been calculated
whether the differences between the Census and by taking the number of counted Census
Council Tax may be definitional (eg differences households and dividing this by the number of
in recording of vacant properties). This analysis assumed occupied Council Tax addresses (the
also allowed an estimate to be produced of the total number of Council Tax addresses minus
number of dummy forms that should have been those counted by the Census as vacant, second
completed by Enumerators. homes and visitor only households). In wards
where the Council Tax implied response rate is
Dummy forms are completed by census substantially lower than the ONC household
enumerators to account for census forms response rate for the LA, it is possible that
that either have not been returned (ie a non- significant enumeration failings, for which the
response) or for which the enumerator has ONC may not have been able to make a robust
determined that they should not be returned adjustment, may have occurred. The table is
(ie a valid non-response such as a vacant ordered by the implied census response rate,
household). For 2001, the types of dummy form with the wards with the lowest response rate at
were: the top of the table.
· Refusal
The ONC household response rate for Tower
· Absent Household Hamlets is 76.1 per cent. Looking at table 3.1.3,
· No contact the wards of Spitalfields and ‘Holy Trinity’
show the largest difference between the ONC
· Vacant
household response rate and the implied Census
· Second/Holiday Home response rate, whilst the wards of Millwall and
East India also demonstrate large differences.
The first three of these can be considered as
some form of non-response. In addition, some
census forms are returned with no residents
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www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Table 3.1.3
Analysis of Council Tax based response rates by 2001 Ward
Ward Name 2001 Council Census Assumed Counted Absolute Implied Census
Tax addresses Vacants, occupied Census Difference Response Rate
2nd homes Council Tax households
and visitor addresses
households
Spitalfields 4,003 67 3,936 2,554 1,382 65%
Millwall 10,355 118 10,237 6,837 3,400 67%
East India 3,016 77 2,939 1,968 971 67%
St. Katherine’s 7,865 318 7,547 5,261 2,286 70%
Grove 2,704 17 2,687 1,875 812 70%
Bow 4,356 57 4,299 3,082 1,217 72%
Park 2,710 13 2,697 1,963 734 73%
St. Dunstan’s 3,719 68 3,651 2,658 993 73%
Blackwall 3,602 384 3,218 2,349 869 73%
St. Peter’s 5,082 53 5,029 3,699 1,330 74%
Shadwell 6,146 172 5,974 4,417 1,557 74%
Weavers 4,904 195 4,709 3,538 1,171 75%
Redcoat 2,656 23 2,633 1,984 649 75%
St. Mary’s 2,740 127 2,613 1,973 640 76%
Lansbury 3,941 63 3,878 3,002 876 77%
St. James’ 3,488 131 3,357 2,605 752 78%
Bromley 4,358 33 4,325 3,457 868 80%
Limehouse 3,900 59 3,841 3,071 770 80%
Holy Trinity 4,054 91 3,963 3,441 522 87%
Totals 83,599 2,066 81,533 59,734 21,799 73%
NB: It should be noted that the above table shows a comparison with the wards as they were on Census day
2001. Since then ward boundaries have changed, the more relevant ones outlined below;
· Spitalfields has reduced in size and is known as Spitalfields and Banglatown, and part of the ward is now
known as Bethnal Green South
· Millwall ward boundary has completely changed its area is now split between new wards Milwall and Blackwall
and Cubitt Town
· East India has had an extension to it ward boundary encompassing some of what was known as Lansbury and
has been renamed as East India and Lansbury.
d) Enumeration Information used if it was judged the ONC process had
Census enumerators collected certain failed. This classification is useful for comparing
information on households where no contact response rates across areas, as we would expect
was made. According to this data, there were the response rates measured by the ONC to be
1,593 (2.07 per cent) vacant households and 295 similar for these LAs. Further information on the
(0.38 per cent) second homes in Tower Hamlets. contingency and borrowing strength strategy can
be found at www.statistics.gov.uk/census2001/
Census returns indicated that there were 160 pdfs/oncinfopaper.pdf , which includes the
(0.21 per cent) visitor only households, and 882 borrowing strength areas in Annex E.
(1.15 per cent) empty households (returned
household forms which have no usual residents, The Borrowing Strength areas for Tower
or very little information on the form). Hamlets and their associated ONC response
rate figures are shown in Table 3.1.4 below. The
These figures are not extreme and are consistent response rate for Tower Hamlets is generally
with expectations for the area. lower than response rate for its borrowing
strength areas. It is also lower than the mean
e) Estimated response compared to other areas response rate for the borrowing strength areas
The ONC contingency strategy used a but the high mean response rate is in part due
classification of ‘similar’ areas (known as to the response rate for Greenwich LA which is
borrowing strength areas) which were to be significantly higher than for other areas. Tower
9
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Hamlets’ response rate is comparable with those would allow differential undercount to be
for the other Borrowing Strength areas. quantified. Because under-enumeration is
disproportionately distributed across areas, the
CCS was stratified according to a Hard to Count
Table 3.1.4 (HtC) index, constructed from the following
ONC Response rates for similar (borrowing 1991 Census variables which are associated with
strength) areas undercount:
Area ONC Response · Multi -occupancy
Rate
Tower Hamlets 75.6% · Unemployment
Borrowing Strength Areas
· Country of birth (which is associated
Hackney 72.1% with language difficulty)
Newham 79.7%
· Private rented accommodation
Southwark 76.8%
Greenwich 85.6% · Number of households imputed in 1991
Islington 77.9% ONC imputation rates by key variables can be
Mean Response Rate for BS Areas 78.4% found at www.statistics.gov.uk/census2001/
imputation_rates_by_variable.asp, and
The ONC response rates for the other local confirm that the above variables were associated
authorities within the same Census Estimation with undercount in the 2001 Census.
Area (EA) as Tower Hamlets are in the table
below. It shows that the response rate for Tower The index categorises Enumeration Districts
Hamlets is broadly consistent with the other LAs (EDs) into 3 groups representing the easiest 40
in the EA. per cent, the next 40 per cent and the hardest
20 per cent of EDs nationally. The sample was
then selected separately within each of these
Table 3.1.5 strata. This meant that the CCS sample had good
Response rates for all LADs in the Estima- coverage of areas with each HtC index value,
tion Area based on 1991 Census data, which was the only
Local Authority ONC Response Rate information available at the time of the 2001
Tower Hamlets 75.6%
Census.
Hackney 72.1%
a) Missing sample
Islington 77.9%
As part of the ONC process, investigations
were carried out into sampled postcodes, with
high levels of CCS only, or Census only counts.
f) Qualitative information obtained about the
If it were found that the CCS or Census was
Census enumeration
enumerated so poorly as to be out of scope of
The analysis of fieldwork intelligence indicates
the ONC (ie the ONC would not be able to
that there were some problems.
compensate for the undercount), these postcodes
· The percentage of direct returns, were removed from the sample.
unplanned Census forms and calls made
to the helpline fell outside the acceptable There were no missing postcodes and no area
range. was excluded from estimation.
· Many enumerators were doubling up
b) Sample balance
or had large workloads. This meant
This analysis assessed whether the selected
that fewer visits could be made by the
sample was adequately balanced across
enumerators to check progress.
indicators associated with undercount (both
across the Estimation Area and also the
3.2 Census Coverage Survey constituent Local Authorities), and also whether
A key element of the One Number Census the CCS was successful in achieving high
was the Census Coverage Survey (CCS) - a response rates, and therefore measuring the
post enumeration survey that was designed undercount in the Census.
to measure undercount in the Census. The
aim was to survey a representative sample The analyses used 2001 Census data, in an
of postcodes across the country, which attempt to examine the balance of the sample
across a number of variables.
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www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Dummy form distribution The map on page 12 shows the spread of
As mentioned in section 3.1 (b), dummy forms dummy non-response forms by ward, with CCS
are completed by census enumerators to account postcodes indicated by red dots. The areas with
for census forms that either have not been the largest percentage of non-response dummy
returned (ie a non-response) or for which the forms (ie the darkest wards on the map) tend to
enumerator has determined that they should not contain a number of CCS postcodes. The fact
be returned (ie a valid non-response such as a that the CCS visited these areas indicates that
vacant household). areas of undercount in these areas are likely to
have been identified. One exception to this was
The refusal, absent, no contact and empty Blackwall ward that was not covered by any CCS
households (which can be thought of as non- postcodes and undercount may not have been
response dummy forms) provide an indication detected.
of response rates across an area, and can be
used to assess whether there is any significant Table 3.2.1 below shows the proportion of
imbalance within the CCS sample selection by Census dummy forms across the Estimation
comparing the proportions of these dummy Area and within the CCS sample for each Hard
forms between the sample and the non-sampled to Count stratum. The difference between
areas. This would show whether the CCS is proportions is not high so does not give cause
likely to provide a sample that underestimates or for concern.
overestimates undercount.
It should be noted that hard to count strata 1
The proportions of census households that were and 2 were collapsed for this Estimation Area,
classified as refusals, no-contact, absent or empty due to the low sample size of hard to count 1.
households are examined. The data used are the See section 3.3 (b) for details.
unadjusted census records - that is prior to the
ONC adjustments. The CCS sampled postcodes Table 3.2.2 below shows the proportion of
within an Estimation Area (EA) are compared dummy forms for each Hard to Count stratum
with the whole of the EA, and the same analysis of each Local Authority in the Estimation Area,
done at LA level. This is also carried out within both across the whole stratum and within the
the Hard to Count (HtC) strata, since we would CCS sample. Again, the differences between
expect the proportions of dummy forms to be proportions are not relatively large.
different across these strata. It is valuable to
look at proportions of dummy forms at both LA
and the EA level because the ONC estimation
system produced estimates first at the EA level,
then apportioned these estimates out to the LAs
within that EA.
Table 3.2.1
Proportion of dummy forms across the Estimation Area and within the CCS sample for
each Hard to Count stratum
Estimation Area Hard to Count Count of dummy Proportion of Proportion of Difference
Index stratum forms in CCS dummy forms dummy forms between
across all areas in CCS proportions
Islington, Hackney 2 135 21.4% 16.8% 2.2%
and Tower Hamlets
3 643 21.2% 21.2% 0.1%
Table 3.2.2
Analysis of proportions of dummy forms across the Local Authorities for each Hard to
Count stratum
Local Authority Hard to Count Count of Count of Proportion of Proportion of Difference
District Index stratum dummy forms households in dummy forms dummy forms between
in CCS CCS across all areas in CCS proportions
Tower Hamlets 2 75 464 20.1% 16.2% 3.9%
Tower Hamlets 3 143 740 20.3% 19.3% 1.0%
Islington 2 60 339 16.7% 17.7% -1.0%
Islington 3 227 1,119 18.2% 20.3% -2.1%
Hackney 2 633 2,876 22.0% 22.0% 0.0%
Hackney 3 273 1,168 24.8% 23.4% 1.4%
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www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Figure 3.2.1
Map to show the percentage of non-response dummy forms for Tower Hamlets
Park
St. James' Bow
Grove
St. Peter's
Weavers Holy Trinity Bromley
Spitalfields Limehouse
St. Dunstan's
St. Mary's Redcoat Lansbury East India
Shadwell
St. Katherine's Blackwall
Legend
CCS Postcodes
Millwall
9% - 10%
>10% - 13%
>13% - 16%
>16% - 19%
>19% - 22%
>22% - 25%
>25% - 28%
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www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
To explore this further, the distribution of the The assumption underpinning the analysis is
proportions of dummy forms are shown below that the recalculated score is highly correlated
in figures 3.2.2 to 3.2.3 on pages 14 – 16, with with the real undercount - that is, that these
the proportion for Tower Hamlets as a whole variables are associated with undercount in
shown in figure 3.2.2 and broken down by hard 2001. From the patterns observed in the CCS,
to count stratum for figures 3.2.3 (b) and (c) there is evidence to suggest that this assumption
is reasonable. The score is calculated as the sum
Figure 3.2.2 shows that there is some CCS of the proportions of:
sample imbalance. In the whole EA there are
· Unemployed persons
a number of EDs that have a dummy form
response proportion of 30 per cent or higher. In · Persons whose country of birth was a
the CCS sample there are very few EDs that have non-English speaking nation
dummy form proportion above 30 per cent.
· Privately rented households
Figure 3.2.3 (b) shows that there is some · Dummy form ‘non-response’ households
CCS sample imbalance in the HtC 2 stratum. · Multi-occupied dwellings
The CCS sample only contains Enumeration
Districts that have a dummy form proportion The derived score is calculated for all postcodes
of 30 per cent or less, whilst the whole LA has across the Estimation Area, and comparisons can
some EDs that have dummy form response be drawn between the score distributions for the
proportions of 60 per cent. However, the Estimation Area/Local Authority and the CCS
population of this stratum is small. sampled postcodes.
Figure 3.2.3 (c) shows that again there is some Section 3.3 (d) Stratification, also looks at the
CCS sample imbalance. There are no EDs recalculated hard to count scores but provides
in the CCS sample that have a dummy form a general analysis on how the area has changed
response proportion of above 30 per cent, in terms of hard to count between 1991 and
whilst in the LA there are some EDs that have 2001. This section focuses on comparing the
dummy form response proportions of over 60 proportions of hard to count areas in the CCS
per cent. However, this apparent imbalance may sample and the rest of the EA or LA
not indicate an underestimation risk if there is
sample in other LAs that represent these harder Figure 3.2.4 on page 17shows the recalculated
to count areas. Hard to Count score distributions for the
whole EA and for CCS sample postcodes. The
Figure 3.2.3 (a) - Distributions of the distributions are reasonably similar, indicating
proportions of dummy forms in each 2001 that the CCS sample was balanced across the EA
Enumeration District for the HtC 1 stratum as a whole.
There is no HtC 1 stratum as this was collapsed Figures 3.2.5 (b) and (c) on page 18 show the
with HtC 2. recalculated Hard to Count score distributions
for the population and sample across the whole
Recalculated Hard to Count score Estimation Area by 2001 hard to count groups.
The Hard to Count score was derived using a
number of 1991 Census variables which were Figure 3.2.5 (b) shows that the distributions
associated with undercount. The score was used are not very similar for the Hard to Count 2
to determine the level of the Hard to Count stratum, caused by the small population and
index for each 1991 Enumeration District in sample sizes. There are large spikes in the CCS
England and Wales. The index was then used sample distribution that suggests the CCS has
within the CCS sampling strategy as the primary over-targeted some areas with the same HtC
stratifier within each Estimation Area, and as a score.
stratum for estimation.
Figure 3.2.5 (c) shows that the distributions are
As the data used to derive the HtC index was not identical for the Hard to Count stratum
from the 1991 Census, there was a risk of the 3. The CCS sample covers most of the range
sample being unbalanced with respect to the that the whole EA covers. The CCS sample has
‘real’ hard to count information. We can assess a higher percentage of EDs with higher scores
this by using a new hard to count score, derived when compared to the whole EA.
from the 2001 Census data, at postcode level.
13
Figure 3.2.2
Distributions of the proportions of dummy forms in each 2001 Enumeration District
www.statistics.gov.uk
14
2004 Local Authority studies: Tower Hamlets
Figure 3.2.3 (b)
Distributions of the proportions of dummy forms in each 2001 Enumeration District for the HtC 2 stratum
www.statistics.gov.uk
15
2004 Local Authority studies: Tower Hamlets
Figure 3.2.3 (c)
Distributions of the proportions of dummy forms in each 2001 Enumeration District for the HtC 3 stratum
www.statistics.gov.uk
16
2004 Local Authority studies: Tower Hamlets
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Figure 3.2.5 (a) is not relevant, as there is no The following table shows the level of
Hard to Count group 1 stratum in Tower undercount identified by the CCS. The One
Hamlets. Number Census was based on dual system
estimation, which combines the numbers of
Figure 3.2.6 on page 19 shows the recalculated people enumerated by the Census and/or CCS
Hard to Count score distributions for Tower and estimates those people missed by both. The
Hamlets Local Authority and for the CCS sample DSE (dual system estimate) column shows this
areas within Tower Hamlets. The distribution figure for each ward. A measurement of the
has a number of spikes but does cover the range Census undercount implied by the CCS can
of scores that are shown in the whole LA. therefore be obtained by dividing the DSE by
the number of people counted in the Census,
c) Localised undercount and the CCS and using this figure as a multiplier. The final
Potential areas of localised undercount were column in the table shows this figure. If the
identified in a number of ways including CCS had found a level of undercount that was
comparing the ONC household response rate similar to that implied by the Council Tax data,
with the response rate implied by Council Tax then there is evidence to suggest that the ONC
(see section 3.1 (c), table 3.1.3). Areas with has made a robust adjustment. If, however, the
high proportions of dummy forms were also CCS had no sample in these wards or it had not
investigated. Where the CCS had visited these found a reasonable level of undercount, then the
wards, it was investigated to check the level ONC may not have been able to make a robust
of undercount that had been observed by the adjustment.
CCS, and whether this looked plausible when
compared to the levels implied by the Council In Tower Hamlets, Bow East ward had the largest
Tax. difference between Census and Council Tax
figures. Ward boundaries have changed since
Census day 2001, and the ward of Bow East in
2003 is made up of parts of several 2001 wards
Figure 3.2.4
Distributions of the recalculated Hard to Count score for the Estimation Area
17
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Figure 3.2.5 (b)
Distribution of the recalculated Hard to Count score for the Estimation Area by Hard to Count group 2
Figure 3.2.5 (c)
Distribution of the recalculated Hard to Count score for the Estimation Area by Hard to Count group 3
18
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Figure 3.2.6
Distributions of the recalculated Hard to Count score for the Local Authority
Table 3.2.3
Census Coverage Survey implied undercount by 2001 ward
HOUSEHOLDS
Ward name No. CCS postcodes Counted in Census DSE DSE/Counted in Census undercount
Census
Bow 4 68 84.2 1.238 19.2%
St Katherine’s 2 9 29.3 3.256 69.3%
Shadwell 3 69 80.9 1.172 14.7%
PERSONS
Ward name No. CCS postcodes Counted in Census DSE DSE/Counted in Census undercount
Census
Bow 4 169 219.8 1.300 23.1%
St Katherine’s 2 39 104.0 2.667 62.5%
Shadwell 3 113 128.1 1.134 11.8%
(Bow and Park). St Katherines and Wapping The CCS has found a high level of undercount
also had large differences between the Council in Bow East ward, with a mean undercount of
Tax figures and Census figures. This comprised 19.2 per cent for households and 23.1 per cent
of two 2001 wards, St Katherines and Shadwell. for persons across the wards from parts of which
The CCS has therefore been investigated in each it was formed. This is a hard to count 2 or 3
of these wards. There was no CCS sample in the area, and so this level of undercount would be
Park ward. expected. The CCS has also found extremely
high levels of undercount in the St Katherines
ward. Overall, the difference between the ONC
19
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
estimate and the Council Tax total for this ward a) Response rates
suggests that the ONC adjustment was robust. The estimated person level response rate for
Tower Hamlets is 75.6 per cent.
d) CCS fieldwork and response rates
No problems were reported that were specific Across the Local Authority, dummy form
to the CCS enumeration, many of the same analysis suggested a household response rate
problems faced by Census fieldstaff (Section 3.1 of 79.7 per cent, whereas the ONC estimated
(f)) were common to CCS fieldstaff. a response rate of 76.1 per cent (ranked 16th
across all LAs in terms of the difference). There
Table 3.2.4 below shows the response rates, were 165 unfilled dummy forms after the
matching outcomes and sum of the dual system imputation process. 3,710 households were
estimates by Hard to Count group. There were imputed into random postcodes.
large CCS only and Census only counts and this
has led to large estimates of persons missed in Table 3.3.1 below shows the estimated response
both, through the ONC process. The CCS has rates by Hard to Count group for this Local
performed in line with expectations. Authority.
3.3 One Number Census process
The One Number Census project (ONC) was Table 3.3.1
set up by ONS for the 2001 Census to address Estimated Response rates by Hard to Count
the fact that it is inevitable that some people group for Tower Hamlets.
and households will not be counted in any Hard to Count Household Person Response
population census. By conducting a large group Response rate rate
post-enumeration survey (the Census Coverage 2 79.3% 80.6%
Survey, CCS) and combining the results of both 3 74.4% 74.6%
the Census and CCS in what is known as a dual
system approach, the aim of the project was
to estimate and adjust the Census database for b) Collapsing in the ONC process
undercount, and to ensure that robust results For the purposes of One Number Census (ONC)
could be obtained for each local authority area. estimation the population was divided into 37
age-sex groups. In addition, each postcode was
Detailed information on the One Number classified into one of three Hard to Count (HtC)
Census can be found in the following links: levels, 1 being the easiest and 3 the hardest. This
means that there were 111 separate estimation
A Guide to the One Number Census:
strata in any given Estimation Area (EA).
www.statistics.gov.uk/census2001/pdfs/
However, in some cases it was not possible to
oncguide.pdf
produce good quality estimates of these groups
separately. In these cases groups were combined,
One Number Census methodology and Quality
referred to as “collapsing strata”. In Tower
Assurance process report:
Hamlets, Hard to Count strata 1 was collapsed
www.statistics.gov.uk/census2001/pdfs/onc_
with Hard to Count strata 2. More details of how
qa_process.pdf
this was applied for Tower Hamlets can be found
at www.statistics.gov.uk/census2001/pdfs/
Analyses into how well the ONC process worked
for Tower Hamlets were carried out as detailed collapsing_strata.pdf
in the sections below.
Table 3.2.4
Response rates, matching outcomes and sum of the missed person estimates by Hard to
Count group for the CCS sample areas in the Local Authority.
Local Authority Hard to Count CCS person CCS only count Census only Matched count Estimate of
group response rate count persons missed
in both
Tower Hamlets 2 84.3% 188 148 838 43.3
Tower Hamlets 3 84.9% 456 238 1,317 76.1
Hackney 2 - 0 0 0 0.0
Hackney 3 71.2% 578 615 1,485 219.6
Islington 2 71.1% 86 151 384 39.8
Islington 3 73.7% 481 512 1,408 162.4
20
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
c) Outliers the analyses in section 3.1 showed that there
Each postcode in the CCS is used to represent were not significant pockets of localised
undercount in a number of postcodes in the poor response. This lessens the risk of
population. When an unusual observation underestimation due to the presence of a large
occurs in a postcode it is likely that it is not numbers of outliers.
representative of other postcodes. In order that
the unusual postcode (referred to as an outlier) d) Stratification
does not have an undue influence on the rest of The ONC estimation process used pre-defined
the population, it is removed from the sample. stratification. These were the Hard to Count
(HtC) index and 37 five-year age-sex groups.
Within the ONC strategy, outliers were The HtC index was based on 1991 Census data,
identified using pre-defined ‘ratio’ limits for and was used to draw the sample and to form
individual observations. The ratio was defined estimation groups. Whilst this was the best
by the ratio of the dual system estimate to the stratification that could be used at the time,
census count for each age-sex observation in there may be areas where the Hard to Count
each postcode. These limits were different for index gave a poor stratification. Analyses have
each Hard to Count stratum. The limits were been undertaken to examine the change between
a ratio of 3 for the Hard to Count 1 stratum, a the 1991 HtC distribution and that implied by
ratio of 4 for the Hard to Count 2 stratum and a the 2001 Census data.
ratio of 5 for the Hard to Count 3 stratum. If an
observation was classified as an outlier through Figure 3.3.1 on page 22 shows how the HtC score
this method, it was not used in the calculation distribution for Enumeration Districts (EDs)
of any model parameters. For example, the CCS has changed from the 1991 Census to the 2001
finds 6 people that the Census missed, and both Census for the whole Estimation Area. A score
the Census and CCS find 1 person. The Census of greater than 0.43 on figure 3.3.1 indicates
will show 1 person, and the dual system estimate that the ED would be a HtC 3 area using 2001
is 7 persons. The ratio for this observation is data. It can be seen that the Estimation Area was
then 7, which is classified as an outlier. This harder to count in 2001 than it was in 1991, with
methodology was based on the data from the more EDs in HtC 3.
simulation studies, which assumed an overall 95
per cent Census coverage. Note that this analysis looks at the overall change
between 1991 and 2001 in the distribution
The Estimation Area had 30 outliers, ranked of hard to count areas across the Estimation
equal 2nd across the 101 Estimation Areas. The Area and LA as a whole. Part of section 3.2 (b)
outliers within this Estimation Area contained also looked at the recalculated hard to count
8.8 per cent of the persons found in the CCS distribution, but in terms of the CCS sample
that were missed by the Census, ranked equal compared with the rest of the EA and LA.
3rd amongst all Estimation areas. This is a high
figure, which may have affected the estimates Figure 3.3.2 on page 22 shows how the HtC score
in this area. There were 10 outliers in Tower distribution has changed from the 1991 Census
Hamlets, ranked equal 5th across all 376 Local to the 2001 Census for Tower Hamlets. As with
Authorities. the EA graph, this shows that Tower Hamlets
is harder to count in 2001 - EDs scoring above
Because this Estimation Area had a large 0.43 would fall into HtC stratum 3, and the 2001
number of outliers, there was an increased score shows a higher proportion of EDs above
risk of underestimating the population. This this level, and many less EDs below this level.
was because in areas where response in the
census was poorest, the ‘fixed cut off ’ outlier Figure 3.3.3 on page 23 shows how individual
strategy tended to identify more outliers than EDs have changed from the 1991 score to the
it was designed to. It was therefore a possibility 2001 score for the Local Authority District.
that some of these observations were valid The graph shows that the area has been subject
representations of the level of undercount in to much change in both directions, with a
non-sampled areas. To determine whether clear trend that HtC scores increased over the
this was the case, the enumeration data were 10-year period. This may indicate a risk of
examined for evidence of localised pockets of underenumeration, although the area is still
non-response - which would be represented mostly HtC 3.
by outliers for several age-sex groups within
the same CCS postcode. In Tower Hamlets,
21
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Figure 3.3.1
Distribution of 1991 and 2001 Hard to Count scores for EDs within the Estimation Area
Figure 3.3.2
Distribution of 1991 and 2001 Hard to Count scores for Tower Hamlets
22
Figure 3.3.3
Scatter plot of 1991 and 2001 Hard to Count scores for each Enumeration District in Tower Hamlets
www.statistics.gov.uk
23
2004 Local Authority studies: Tower Hamlets
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
e) Household and person imputation results 2) There was a high level of dependence for
Detailed information on imputation can be missed households, which results in an
found at www.statistics.gov.uk/census2001/ underestimate of total households and
pdfs/sc9908.pdf total people. Because the under-estimate
of people will be within wholly missed
The ONC imputation process imputed people households, the CCS pattern will show an
as part of wholly imputed households and also overestimate.
into counted households. There was no explicit
In general, of these two scenarios, the second
restriction on how many people were imputed
is the most likely to have occurred. However,
into these two categories, the only restriction
a firm conclusion could only be reached if
was on the total number of people imputed
supported by other external evidence, of
into a Local Authority. Since the imputation
dependence or of over-estimation of households.
of households (rather than people) was carried
out as the first step, any people remaining to
Within this Estimation Area, the imputation
be imputed were then placed into counted
process imputed 18.9 per cent of the imputed
households. Therefore, the patterns observed
people into counted households. The CCS
in the CCS may be very different to those
measured this proportion to be 16.5 per cent.
created by the imputation methodology. There
This was the 23rd largest difference in this
are a number of factors that will contribute
direction across all 101 Estimation Areas.
to any extreme differences, mainly relating
to households and people being estimated
At LA level, the imputation process imputed 13.3
separately. This means that any under or over-
per cent of the imputed people into counted
estimation of either will affect the proportions of
households. The CCS measured this proportion
households or people that are imputed.
to be 17.7 per cent. This was the 203rd largest
difference in this direction across all 376 Local
For areas where the imputed proportion is
Authority Areas.
significantly higher than that measured by the
CCS there are three interpretations:
There is not a large difference between the
1) There was an underestimate of total imputation process and the CCS with Tower
households, therefore more imputed Hamlets’ figures (ranked 203th of 376) so there
people went into counted households. is insufficient evidence of a problem here.
2) There was a high level of dependence
between Census and CCS for people
4 Population definitions
within counted households, and so the
CCS pattern shows an underestimate. The 2001 Census was conducted on a usual
More information on dependency can residence base, that is, people were asked to
be found at www.statistics.gov.uk/ fill in details on a form at their place of usual
census2001/pdfs/dependency_paper.pdf residence.
3) There was an overestimate of total people, It is likely that areas which have high numbers
therefore the remainder were placed into of mobile people where usual address is not easy
counted households. to define will be difficult to count. People with
Of these three scenarios, generally the first two second homes, students who live at different
are the most likely to have occurred. However, addresses during term time and holidays fit this
a firm conclusion could only be reached if category, as do many members of the armed
supported by other external evidence, of forces who are often moved from base to base.
dependence, under-estimation of households or Quantifying the numbers of people that are
over-estimation of people. Conversely, for areas wrongly missed off forms for this reason is
where the imputed proportion is significantly very difficult, due to the lack of evidence that is
lower than that measured by the CCS, there are available - the 2001 Census was conducted solely
two interpretations: on a usual residence base, with little information
on visitors collected, therefore comparisons with
1) There was an overestimate of total figures collected on a different base cannot be
households, therefore too many imputed made.
people went into wholly imputed
households.
24
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Students non residential, demolished, derelict or ‘Late
A quality assurance of student estimates was returns’ (i.e. returned after the processing cut off
carried out as part of the ONC process. More date)) these were excluded from the analysis. If,
information can be found in the following links: however, the absence could not be explained the
details of the individual records were recorded
www.statistics.gov.uk/census2001/pdfs/ and summary reports were produced for each
students.pdf Estimation Area (EA), recording the number of
forms missed.
www.statistics.gov.uk/census2001/pdfs/onc_
key_findings.pdf (under section 4.2) The main reasons for forms not being processed
were:
The number of students that live in Tower · Forms were not received from the field or
Hamlets during vacation time but were living received too late
away in term-time was 755. This is ranked 371st
among all LAs, so is not particularly high. · Forms lost in the system during system
crashes
An analysis on student numbers based on · Some forms were misrecognised and
comparisons with census figures and council therefore delivered as part of a different
tax records has been conducted. This analysis EA/LA
highlights areas that have a large difference
between these two figures. For the EA as a whole, there were 2,155
unprocessed forms, 1,431 of which were late
This analysis shows that Tower Hamlets (shown forms. In Tower Hamlets LA there were 690
below) is ranked 25th highest of the 376 LAs in unprocessed forms distributed over a number of
terms of the difference between student houses EDs, which is 0.86 per cent of total households.
in council tax records and student properties There were 2 EDs with 25 or more forms
counted in the Census. The second column in a block missing. These numbers are not
shows households which are occupied solely by significant, and are within the acceptable level
students and therefore gaining an exemption for ONC imputation.
from council tax. There will also be many
households in Tower Hamlets that contain
students living with non-students that will not 6 Other - communal establishments
appear in these figures. This section contains information on communal
establishments (such as residential homes,
student halls).
Table 4.1
Comparison of students in the Census and The 2001 Census shows that Tower Hamlets
Council Tax records has 1,986 persons living within 162 Communal
Establishments. There is some evidence of
Tower Total 2001 Census Difference
Hamlets Exemption - All Student problems with the enumeration of Communal
Class N Properties
(CTB1 Establishments in Tower Hamlets.
Student
Exemption)
The ONC Quality Assurance process included
1,304 832 472
an assessment of Communal Establishments, in
particular Halls of Residence. As a result Tower
Hamlets received an adjustment. For more
5 Processing
details see www.statistics.gov.uk/census2001/
As the data was processed, checks were carried pdfs/onc_key_findings.pdf
out to ensure that the delivery of the data for
the Estimation Area data was complete. The
data was checked to ensure that the Census 7 Other -administrative sources
Household form numbers were in sequence
The ONC Quality Assurance (QA) process
with no unexpected gaps. The identities of the
involved comparisons with various
missed forms were then compared to other data
administrative data sources, as detailed in the
and information (Enumerator Record Books
individual QA information packs for each Local
(ERB), enumerator-completed summary forms
Authority.
and the geography database). If Household
forms had been missed for a valid reason (i.e.
25
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
Further analysis of administrative sources was Table 7.1 compares the 2001 MYEs and Census
completed as part of the LA Studies program. counts, as appropriate, with each of the
The administrative sources used, both by the administrative data sources and the previous
ONC QA processes and the LA Studies, are (2000) MYE. This table also gives Tower
detailed below. Hamlets’ ranking amongst local authorities in
England and Wales, for each comparison, with
Council Tax - Council Tax dwelling counts LAs ranked first having the largest difference
for 2001 were compared with the Census between the two counts.
results for each Local Authority. More detailed
comparisons of Council Tax counts of occupied The administrative sources show a mixed
and vacant dwellings with the Census results picture. Some of the sources suggest that the
were also completed. Census has underestimated the population,
whilst other sources indicate that the Census
Electoral Roll - The revised 2001 Mid -Year has overestimated the population. They also
Estimates (MYEs) for people aged 18 years and vary when compared to the national averages,
over were compared with the Electoral Roll data. some are lower than the national average, whilst
others are higher than the national average. This
Patient Register - The revised 2001 MYEs have is not necessarily a cause for concern given the
been compared with the NHS Patient Register variability in the quality of the administrative
data (adjusted and unadjusted) for 2001. sources, mainly due to definitional and timing
differences. There is a large difference between
Pensions - The revised 2001 MYEs for people the number of households on Council Tax and
aged 65 years and over have been compared the Census, although when occupied counts are
with the year 2000 Department for Work and compared as in Table 3.1.2, there is very little
Pensions (DWP) Pensions data. difference.
Child Benefit - The revised 2001 MYEs for
people aged 0 – 14 were compared with the 2001 8 Conclusions and recommendations
Child Benefits data. There were 3,367 more dwellings recorded on
Council Tax data than counted in the Census.
Schools Census - The revised 2001 MYEs However, most of this difference is vacant
for people aged 5 – 14 years inclusive were households, and there are 79 more occupied
compared with the 2001 Schools Census data. households recorded in the Census. The CCS
sampled in most of the wards that had the
Table 7.1
Comparisons of Revised 2001 MYE with administrative sources
Source compared Ranking (/376) Source Revised 2001 MYE Source as % of National Average
to 2001 MYE Population MYE
2000 MYE 374 186,700 201,600 92.6% 101.3%
2001 Electoral Roll 356 139,291 151,400 92.0% 98.5%
data (18+ Only)
2000 Pensions data 22 18,631 18,500 100.7% 98.5%
(65+ Only)
2001 School Census 125 27,779 27,000 102.9% 100.6%
Data (5-14 Only)
2001 Child Benefit 67 42,200 42,800 98.6% 99.2%
Data (0-14 Only)
2001 Health 78 213,411 201,600 105.9% 105.0%
Register Data
2001 Adjusted 29 218,588 201,600 108.4% 104.4%
Patient Record
Data
Source compared Ranking (/376) Source Census Source as % of National Average
to Census Data Households Households Census
2003-04 Council Tax 2 86,666 80,800 107.3% 101.2%
Data
NB: The Mid Year Estimates in this table have been rounded
26
www.statistics.gov.uk 2004 Local Authority studies: Tower Hamlets
largest differences and there is evidence that the
undercount was picked up by the CCS.
There was a large change in the Hard to Count
scores for Tower Hamlets between 1991 and
2001, and there was also a large number of
outliers. However, these problems alone do not
give cause for concern, and are not backed up by
other evidence.
None of the other analyses carried out in this
report have highlighted significant risks, and
we have found no basis on which to make an
adjustment to the estimate of the population of
Tower Hamlets.
27
