Homework -
Hypothesis Testing: Continuous Variables (2 Sample)
DIRECTIONS: When computation is required, show all work neatly. Feel free to use some creativity in the analytical approach you take. As usual, do the problems by hand as well as with Minitab. Attach the (marked up) Minitab output showing that you know what is relevant to look at in the output, how it helps you to make the relevant decisions, and whether it agrees with your hand calculations.
Essay (15 points)
- Describe in your own words what Minitab means when it refers to the data
as being in a single column or in different columns when doing a two-sample t
test.
Multiple Choice (10 points)
- The statistic t is only employed when
a. N is large.
b. N is small.
c. the sample standard deviation is known.
d. the population standard deviation is known.
e. the population standard deviation is unknown.
- As the alpha level becomes more conservative (e.g., .01 rather than .05), the critical value of t will
a. decrease.
b. increase.
c. remain the same.
d. insufficient information is given.
Problems (Please use the 6 step procedure for doing hypothesis tests that we use in class.)
- A random sample of a dozen Wisconsinites drink an average of 4.9 drinks per
week with a standard deviation of 2.3, while a similar sample of New Yorkers only
drink 3.7 drinks per week with a standard deviation of 2.1. Do the people in these
two states differ in their drinking behavior? Note, just do this by hand. In other words, I am not requiring Minitab for this problem. (25 points)
- In a study aimed at determining the effectiveness of a new diet, an insurance
company selects a sample of nine overweight men between the ages of 40 and 50
and obtains their weight measurements both before the diet begins and sixty days
after it is instituted. Given the data below, is the diet effective? (25 points)
SUBJECT |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
Before |
202 |
237 |
173 |
161 |
185 |
210 |
209 |
191 |
209 |
After |
180 |
221 |
175 |
158 |
180 |
197 |
205 |
196 |
185 |
- In the study above, an extraneous variable is the fact that subjects may lose
weight during the 60 day time period for reasons other than the diet. Therefore,
we decide to include a control group. This group will be matched in weight to
the experimental subjects, but will not receive the diet. Their data is given
below. Is the diet effective? Feel free to be creative in your solution to this
problem because there are multiple ways of solving based upon what we have learned so far. (25 points)
SUBJECT |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
Before |
203 |
235 |
175 |
159 |
183 |
210 |
209 |
192 |
201 |
After |
207 |
231 |
172 |
164 |
187 |
204 |
215 |
215 |
184 |
Copyright © 1997-2015 M. Plonsky, Ph.D.
Comments? mplonsky@uwsp.edu.