Question - statman by shitingting

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									The Setting: You work as a consultant for a firm that specializes in workplace health. You have recently been put
been hired by a company with 80 employees, half men and half women, that is considering instituting an employe
they have specific concerns over obesity and cholesterol levels among their employees. They have provided you w
data. You can find this data on the tab titled "Health Exam Results Data."
alth. You have recently been put on a team that has
considering instituting an employee wellness program as
ployees. They have provided you with employee health
Sex      Age        Height          Weight    Cholesterol
Female         17            64.3       114.8           264
Female         32            66.4       149.3           181
Female         25            62.3       107.8           267
Female         55            62.3       160.1           384
Female         27            59.6       127.1             98
Female         29            63.6       123.1             62
Female         25            59.8       111.7           126
Female         12            63.3       156.3             89
Female         41            67.9       218.8           531
Female         32            61.4       110.2           130
Female         31            66.7       188.3           175
Female         19            64.8       105.4             44
Female         19            63.1       136.1              8
Female         23            66.7       182.4           112
Female         40            66.8       238.4           462
Female         23            64.7       108.8             62
Female         27            65.1        119              98
Female         45            61.9       161.9           447
Female         41            64.3       174.1           125
Female         56            63.4       181.2           318
Female         22            60.7       124.3           325
Female         57            63.4       255.9           600
Female         24            62.6       106.7           237
Female         37            60.6       149.9           173
Female         59            63.5       163.1           309
Female         40            58.6        94.3             94
Female         45            60.2       159.7           280
Female         52            67.6       162.8           254
Female         31            63.4        130            123
Female         32            64.1       179.9           596
Female         23            62.7       147.8           301
Female         23            61.3       112.9           223
Female         47            58.2       195.6           293
Female         36            63.2       124.2           146
Female         34            60.5        135            149
Female         37             65        141.4           149
Female         18            61.8       123.9           920
Female         29             68        135.5           271
Female         48             67        130.4           207
Female         16             57        100.7              2
Male           58            70.8       169.1           522
Male           22            66.2       144.2           127
Male           32            71.7       179.3           740
Male           31            68.7       175.8             49
Male           28            67.6       152.6           230
Male           46            69.2       166.8           316
Male   41   66.5    135     590
Male   56   67.2   201.5    466
Male   20   68.3   175.2    121
Male   54   65.6    139     578
Male   17    63    156.3     78
Male   73   68.3   186.6    265
Male   52   73.1   191.1    250
Male   25   67.6   151.3    265
Male   29    68    209.4    273
Male   17    71    237.1    272
Male   41   61.3   176.7    972
Male   52   76.2   220.6     75
Male   32   66.3   166.1    138
Male   20   69.7   137.4    139
Male   20   65.4   164.2    638
Male   29    70    162.4    613
Male   18   62.9   151.8    762
Male   26   68.5   144.1    303
Male   33   68.3   204.6    690
Male   55   69.4   193.8     31
Male   53   69.2   172.9    189
Male   28    68    161.9    957
Male   28   71.9   174.8    339
Male   37   66.1   169.8    416
Male   40   72.4   213.3    120
Male   33    73     198     702
Male   26    68    173.3   1252
Male   53   68.7   214.5    288
Male   36   70.3   137.1    176
Male   34   63.7   119.5    277
Male   42   71.1   189.1    649
Male   18   65.6   164.7    113
Male   44   68.3   170.1    656
Male   20   66.3    151     172
1. The data from your sample of 80 employees can be found on the tab labelled "Health Exam Results Data." The fasting to
as "cholesterol". Levels below 200 mg/DL are considered normal, levels between 200 and 240 (inclusive) are considered abo
are considered high risk. In addition to this variable, there are four more variables in this data set: "sex" which can have a va
"height (inches)"; and "weight (lbs)". The first step to this analysis is to generate some descriptive measures.

For each of the following points, create the chart and/or graph that best displays the data:
a) Show the breakdown of your sample by gender
b) Show the distribution of cholesterol across all participants.
c) Show the distribution of weight across all participants

Additionally, you want to generate some tables of summary statistics.
d) Create one table that calculates summary measures of cholesterol and weight across all 80 participants.
e) Create a second table that calculates summary measures of cholesterol and weight broken out by gender.

Based on the graphs and tables created in parts a-e:
f) What preliminary conclusions can you draw regarding the differences in cholesterol between male and female employees
"Health Exam Results Data." The fasting total cholesterol measurement (mg/dL) is recorded
 200 and 240 (inclusive) are considered above normal/moderate risk, and levels above 240
s in this data set: "sex" which can have a value of either "female" or "male"; "age (years)";
 ome descriptive measures.

the data:




across all 80 participants.
ight broken out by gender.


erol between male and female employees of this company?
2. A healthy cholesterol level is <200. The company wants no more than 25% of its employees to have cholesterol levels t

a. Construct a 95% confidence interval for the proportion of employees who have cholesterol levels higher than 200.
b. Interpret your findings with respect to the company's 25% target.
ees to have cholesterol levels that exceed 200.

rol levels higher than 200.
3. Five years ago, this company adminstered the same basic health exam to its employees. At that time, it was found that th
274.15. This is too high according to health guidelines. You have been asked to determine if the cholersterol level of the em
administered 5 years ago.

a. State your null and alternative hypotheses.
b. Conduct a test of the hypothesis that the mean cholesterol level has not changed since the health exam given 5 years ago
c. Based on your analysis, what conclusion can we draw about the cholesterol level of the current empoyees?
d. If the goal of the company's wellness program is to reduce the cholesterol levels of its emplyees, should the company ad
will educate employees about ways they can lower their cholesterol?
At that time, it was found that the mean cholesterol level of the employees was
if the cholersterol level of the employees has changed since the exam that was




he health exam given 5 years ago.
 urrent empoyees?
mplyees, should the company add a component to their wellness program that
4. One manager has conjectured that the men have bad dietary habits and probably have high cholesterol readings,
which should be the focus of the wellness program. We would like to test the hypothesis that male cholesterol readings
are different from female cholesterol readings.
a) Conduct an ANOVA to evaluate whether or not there is a significant difference in cholesterol readings between males
and female.
b) Summarize and Interpret the results of your test.
esterol readings,
 cholesterol readings

dings between males
5.One manager suggests that the company may be able to check on the progress of the wellness campaign by observing cha
more costly cholesterol reading. The body-mass index is defined as the ratio of the weight to the square of the height, mult
the weight is measure in pounds. BMI = 703*Weight/(Height^2). There is also some discussion that changes in the BMI may
readings than female cholesterol readings.
a) Create the BMI variable and a dummy variable for sex, called Male, which is zero for females and 1 for males.
b) Estimate a multiple regression model that includes the sex dummy, BMI and an interaction variable between BMI and sex
c) Calculate predicted values for cholesterol readings for both men and women at BMI values of 25 and 30.
d) Summarize and interpret the results of this model. Is BMI relevant for the program? What do you tell the management te
men and women?
 campaign by observing changes in the body mass index instead of redoing the
e square of the height, multiplied by 703 if the height is measured in inches and
 hat changes in the BMI may be more effective in reducing male chlesterol

and 1 for males.
riable between BMI and sex, as independent variables.
25 and 30.
 you tell the management team about the relative importance of the BMI for
6. Shortly after you publish your findings in a report, you receive a call from a small manufacturing company in
Mississippi. The copmany employs 250 workers in a rural area. They too have investigated their employees cholesterol.
However, they are confused because their statistical findings showed nothing significant. What do you tell them and
why?
7. The variable the company is most interested in understanding/explaining is cholesterol. You were also given variables
that indicated the gender, height, and weight of the study participants. If this were a real research project, you would
surely collect other data to use as control variables. For each of the following variables, explain why you would, or would
not, want to collect the data to use in your analysis: a) normal dietary habits, b) use of cholesterol lowering medications,
c) smoking habits, d) music preference, and e) brand of car owned.




ANSWER KEY
A few weeks after you finish your report, your boss knocks on your door. She is very concerned about the data
and says "the distribution looks a little off to me. Based on data from the Framningham Heart Study, the 99%
Confidence Interval for total cholesterol in the US is approximately 150-350. Single digit total cholesterol is not
compatible with life and total cholesterol over 1000 is usually only seen in genetic disorders. Your data is very
troubling. Can you investigate further to see what is going on?"

Tell me (a) what you would do next (and WHY!!!), and (b) what lessons you might take away from this?
rned about the data
 rt Study, the 99%
al cholesterol is not
 . Your data is very


y from this?

								
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