Introduction to Statistics and
Biostatistics and Definitions
1. WA 900 D184 1991
Daniel, Wayne W.
Biostatistics: A Foundation for Analysis in the Health Sciences
2. WA 950 D272 2004
Dawson, Beth Trapp, Robert G.
Basic & Clinical Biostatistics
Lange Medical Books/ McGrow-Hill NewYork 2004
3. WA 950 G545 2002
Glantz, Stanton A.
Primer of Biostatistics
McGrow-Hill NewYork 2002
4. WA 950 A733 2002
Statistical Methods in Medical Research
Blackwell Science Oxford 2002
This course teaches the basic skills needed to critique the
medical literature by providing a fundamental
understanding of biostatistics.
The primary purpose of this course is to teach you basic
skills to critique the medical literature and need for
statistical consultancy when designing, conducting and
reporting a research. As future physicians you have an
obligation to remain current in your field of practice and to
treat patients according to generally accepted standards
of care. To do this well you will need to read those
journals that are considered the most important sources
of new information impacting on your field of medicine.
For example, internal medicine physicians generally read
the New England Journal of Medicine (NEJM) which is
published by the Massachusetts Medical Society.
Perhaps the most influential medical journal, its articles
are widely reviewed by the media. Most surgeons read
the Annals of Surgery. In short, each field of medicine
has its own specialty journals.
As your patients hear media reports about the latest
research results, they will most certainly ask for your
Should adult patients take antioxidants to help
prevent heart disease?
Do the potential benefits of hormonal replacement
in postmenopausal women outweigh the potential
STATISTICS and BIOSTATISTICS
Statistics is the art and science of data. It deals
•Summarizing- Presenting Data
• Reaching decisions or
discovering new knowledge
Biostatisitcs is the application of statistical
methods to health sciences.
Basic tasks of statistics
•To draw inferences concerning the underlying
These are devices for organizing data and may be:
(i) tabular (ii) graphical (iii) numerical
Much of the statistical investigations are carried
on samples. Conclusions about the population are
thus drawn from the observations carried out on
these samples. Statistical methods which are used
for making inferences about the population are
based on probability theory and are called
Data : Set of values of one or more variables recorded
on one or more observational units.
Observation (case): Individual source of data.
Variable: This is a quantity which varies such that it
may take any one of a specified set of values. It may
be measurable or non-measurable.
Population: A collection, or set, of individuals,
objects, or measurements whose properties are to be
Sample: A subset of the population, selected in such a
way that it is representative of the larger population.
Parameter : A summary value which in some
way characterizes the nature of the population in
the variable under study.
Statistic : A summary value calculated from a
sample of observation.
Sources of data
1. Routinely kept records
2. Published data sources
3. Data on electronic media
4. Surveys and Experimental research
6. Generated or artificial data
Types of Data
1. Qualitative Data
Results from a variable that asks for a quality
type of description of the subject.
2. Quantitative Data
Results from obtaining quantities-counts or
Scale of measurement
Severity of disease
Two More than two Income level
Disease – or + Gender(M;F)
# of birth
# of death
Why should medical students learn biostatistics?
1. Medicine is becoming increasingly QUANTITATIVE.
• The aim is to improve the Health Status of the
• We have to clarify the relationships between certain
factors and diseases.
• Enumarate the occurances of diseases
• Explain the etiology of diseases (which factors
cause which diseases)
• Predict the number of disease occurence
• Read, understand and criticize the medical
Why should medical students learn biostatistics?
2. The planning, conduct and interpretation of
much of medical research are becoming
increasingly reliant on statistical methods.
How many patients must be treated?
How do we have to allocate the subjects to treatments?
What are the other factors which may influence the
Under which conditions must the study be conducted?
Is matching necessary?
Is blinding (single blinding or double blinding) necessary?
Is there a need for a control group?
Shoud the placebo effect be considered?
Which experimental design technique is more appropriate?
Distribution of Women with a Diagnosis of Distribution of Healthy Women Among
Tromboembolism Among Blood Groups Blood Groups
Blood Group Frequency % Blood Group Frequency %
A 32 58.2 A 75 51.7
AB 4 7.3 AB 8 5.5
B 8 14.5 B 19 13.1
O 11 20.0 O 43 29.7
Total 55 100.0 Total 145 100.0
In a follow up study 609 males between ages of 40 to
76 free of coronary heart disease (CHD) were
examined from 1990 to 1999. At the end of the period
71 new cases of CHD were identified. The primary
goal of this study was to evaluate the association
between obesity and the incidence of CHD. The
results were as follows:
Risk Ratio= R
Obesity 27 / 122
Disease Yes No Total R=
44 / 487
CHD+ 27 44 71
CHD- 95 443 538
The risk of CHD is 2.45
Total 122 487 609
times higher among obese