1) Bandura, Blanchard, and Ritter (1969) conducted an experiment that provided individuals with one of four treatments for their intense fear of snakes.One group worked with a model – a person who handled a 4-foot king snake and encouraged others to imitate her.One group watched a film of adults and children who enjoyed progressively closer contact with a king snake.A third group received desensitization therapy, and a fourth group served as a control, receiving no treatment.The numbers of snake-approach responses after treatment are listed in the table.A higher number of snake-approach responses indicates that the individual was willing to approach a snake more often.

 

Type of Treatment
Model	Film	Desensitization	Control
29	22	21	13
27	18	17	12
27	17	16	9

 

Perform a hypothesis test to determine if there is a significant difference between the groups in the number of snake-approach responses.Show all necessary components of a full hypothesis test, including a source table.Assignment 3f

Unit review

 

1) Bandura, Blanchard, and Ritter (1969) conducted an experiment that provided individuals with one of four treatments for their intense fear of snakes.  One group worked with a model – a person who handled a 4-foot king snake and encouraged others to imitate her.  One group watched a film of adults and children who enjoyed progressively closer contact with a king snake.  A third group received desensitization therapy, and a fourth group served as a control, receiving no treatment.  The numbers of snake-approach responses after treatment are listed in the table.  A higher number of snake-approach responses indicates that the individual was willing to approach a snake more often.

 

 

Type of Treatment   

Model Film Desensitization Control   

29 22 21 13   

27 18 17 12   

27 17 16 9  

 

Perform a hypothesis test to determine if there is a significant difference between the groups in the number of snake-approach responses.  Show all necessary components of a full hypothesis test, including a source table.

 

2) What is the effect size for this result?  Is this a large effect?

 

3) An employer wants to know what types of activities encourage her employees to exercise.  The first month, she gave out information on the health benefits of exercise; the second, she sent daily emails encouraging physical activity; and in the third month, she gave health insurance bonuses for amount of exercise.  She recorded the number of times 4 of her employees exercised in each of the three months.  Can she determine if there is a significant difference in the number of days exercised between the three types of activities?  Again, show all necessary components of a hypothesis test, including a source table.

 

 

Employee Month 1 (Info) Month 2 (Emails) Month 3 (Bonuses)   

1 4 7 29   

2 6 7 26   

3 2 11 24   

4 3 9 21  

 

 

4) Calculate a Tukey’s HSD post-hoc test for the difference between Month 2 and Month 3.  Is the difference significant?  Was a post-hoc test necessary to determine this?

 

 

 

 

5) A market testing company wants to know if there is a difference in preference between two new types of chocolate bar.  They also want to know if there is a gender difference.

 

a) How many cells would this ANOVA have?

 

b) What are the independent and dependent variables?

 

c) Here is the source table for this study.  Write a conclusion for these results.

 

 

Source SS df MS F   

Gender 6.24 1 6.24 6.50   

Chocolate bar 20.24 1 20.24 21.08   

Gender*Chocolate 8.99 1 8.99 9.36   

Within 11.49 12 0.96   

Total 46.96 15  

 

d) What is the effect size for the interaction effect?

 

6) Find the mistakes this source table.

 

 

Source SS df MS F   

Between 1621 2 810.5 81.318   

Subjects 45.825 5 91.65 0.919   

Within 99.675 10 9.967   

Total 1866.50 17 109.79  

 

7) What type of ANOVA is the source table in #6 for?

 

8) What is the main factor that differentiates whether you should calculate a t statistic or an F statistic?

 

9) How many types of ANOVA have we covered?  What feature or features distinguish between them?

 

10) Look back to the graphic you created to help you choose which z or t test to use (or use one of the graphics from the answer key).  Modify the graphic to include the different types of ANOVA from this unit.