Statistics for the Behavioral Sciences
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3.docx
Statistics
1.(14 points). You’re a concert promoter and want to know who spends more on average per concert ticket, people who identify primarily as country fans or people who identify primarily as death metal fans. You find 14 death metal fans (mean age = 16) who spend on average $47 per ticket with a variance of 52. You find 14 country fans (mean age = 47) who spend on average $58 per ticket with a variance of 78. Use the appropriate t-test to compare the means with a 2-tailed test and an alpha level of .05. What are some potential problems with the way this study was done?
df =
Pooled variance (S2pooled) =
t =
Critical value of t =
Do you reject H0? =
What is a potential confounding variable in the study and how might it have affected the results?
2.(5 points). What are the main differences between a one-sample t-test, a t-test for independent samples, and a paired-sample t-test?
3.(10 points). You just developed a new diet (the Woodbury Beach Diet) designed for weight loss and want to do test whether or not it’s effective. You get a sample of 10 people and record their weights. You put them on the diet for 6 months then weight them again, resulting in the following data:
|
|
Weight |
Weight |
|
|
After |
Before |
|
Sub 1 |
177 |
167 |
|
Sub 2 |
123 |
123 |
|
Sub 3 |
127 |
135 |
|
Sub 4 |
192 |
212 |
|
Sub 5 |
320 |
345 |
|
Sub 6 |
239 |
264 |
|
Sub 7 |
107 |
102 |
|
Sub 8 |
221 |
233 |
|
Sub 9 |
137 |
144 |
|
Sub 10 |
158 |
171 |
The standard deviation of your data is 12.01. Use a paired sample t-test to see if your diet resulted in significant weight loss at the .05 level.
