1. A researcher is interested in whether eating an apple a day keeps the doctor away. So, she recruits a group of students and assigns half to a control group (n = 8), and half to the experimental group that eats an apple each day (n = 17). After one week, she measures how healthy each group feels on a scale of 0-10. The average for the control group is 6, with a variance of 70, and the average of the experimental group is 9.5, with a variance of 82. Was her hypothesis supported?
a. Complete 5 steps of hypothesis testing by hand.
i. State the research and null hypothesis.
ii. Determine the characteristics of the null distribution.
iii. Determine alpha, critical value, and rejection region.
iv. Calculate the probability of obtaining your data.
v. Make statistical decision.
. Compute an effect size
c. Write results in APA style
2. Suppose the researcher wants to conduct the same study, but she wants to add a group that also takes a multivitamin each day. Her data is listed below. Was there a difference in the healthy ratings across groups?
Control Group
Apple a Day Group
Multivitamin Group
5
9
9
7
8
8
4
9
7
4
8
8
5
5
7
6
6
6
3
7
8
a. Complete 5 steps of hypothesis testing by hand.
i. State the research and null hypothesis.
ii. Determine the characteristics of the null distribution.
iii. Determine alpha, critical value, and rejection region.
iv. Calculate the probability of obtaining your data.
v. Make statistical decision.
. Compute an effect size
c. Write results in APA style
3. Suppose then that the same researcher wants to take the same study, but this time add biological sex as an independent variable. So, she collects 180 participants, and divides them evenly into sex (males and females), and an experimental group (Control, Apple a Day, Multivitamin group). The table of means and the ANOVA table are below. Use them both to test for a main effect of sex, main effect of experimental group, and an interaction effect.
Control
Apple
Experimental
Male
M = 4.70, SD = .50
M = 6.30, SD = .80
M = 7.00, SD = .75
Female
M = 8.50, SD = .75
M = 7.00, SD = .60
M = 9.75, SD = .55
SS
df
MS
F
p
Total
595.00
Gende
4.75
Experimental
7.25
Gender x Experimental
3.00
E
o
580.00
a. Complete 5 steps of hypothesis testing by hand for the two main effects and interaction effect.
i. State the research and null hypothesis.
ii. Determine the characteristics of the null distribution.
iii. Determine alpha.
iv. Calculate the probability of obtaining your data.
v. Make statistical decision.
. Compute an effect size
c. Write results in APA style
4. Perform the following statistical tests in SPSS and write up the results in APA style. Be sure to upload a .pdf of your output window with the assignment
a. Open Nathan’s Hot Dog Eating contest, SHORTENED in SPSS. Perform an independent samples t-test to see whether gender affects the rate of hot dogs eaten per minute.
. Open the Class Survey Data, and perform a one-way ANOVA to see if Year in School predicts Age.
c. Also in the Class Survey Data, perform a factorial ANOVA to see whether Year in School and Class predict height.