EMBA 8150 Regression
Assignment
A researcher is trying to determine if exercise affects
different people differently. Specifically, when people exercise, there is an
increase in a protein called BDNF (Brain derived neurotrophic factor). Is this Increase in BDNF different among males
and females, and is it different among different ethnicities?
The dataset provided shows data on Increase in BDNF in the body due to Exercise, for people in the age range of 1825, along with their Gender and Ethnicity.
1.
Create a Histogram of the variable Exercise to look at its distribution.
Compute the Mean and Standard Deviation of the variable as well.
2.
Create a Pivot table in Excel to analyze the Increase in BDNF by Ethnicity and Gender simultaneously. The table should look as follows, with the
Average, Standard Deviation, and the Count values for Increase in BDNF in each of the cells:
Column Labels 

Row Labels 
Female 
Male 
Grand Total 
African 



Asian 



Caucasian 



Grand Total 



Interpret the table – what can you
say about the impact of Gender and Ethnicity overall? Does there seem to
be an interaction between Gender and
Ethnicity? In other words, is the
impact of Gender on Increase in BDNF different for different Ethnicities?
3.
Create a scatterplot of Increase in BDNF and Exercise.
Make sure Increase in BDNF is on the Y axis. Interpret.
4.
Perform a multiple regression analysis using the
dataset provided (use all the Xs available for the
regression), to predict Increase in BDNF in the body. For Gender, code Male as
1 and Female as 0 (baseline). For Ethnicity, create two dummies, one for Asian
and one for African (keep Caucasian as the baseline).
Note that in Excel, all the Xs that you will
use must be in contiguous columns.
5.
Is the regression significant overall? What does
that mean?
6.
Is each of the variables in the model
significant at the 5% level? Interpret.
7.
What is the Rsquared value? What does it mean?
Now run the regression again after removing variables that are not
significant at the 5% level.
(remember that you may have to move data in
the worksheet so that the variables left in the regression are all in
contiguous columns).
8.
What is the final equation to predict BDNF
increase? What would your model predict as the increase in BDNF for a person
who exercises 20 minutes, and is a Caucasian Female?
9.
Interpret the coefficients for Asian and
African.
10. If
you want to improve the Rsquare value of the model, is increasing the sample
size the best way? Why or why not?