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Homework #5 Name ______________________________

Chapters 9 & 10

 

  1. What is the difference between a within-subjects design and a between-subjects design? (1pt)

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  2. What are confounding variables? (1 pt)

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    2b. How can confounding variables be controlled? (½ pt)

     

     

     

  3. What is random assignment and why is it important? (1 pt)

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  4. What is the rationale that allows us to combine the variance estimates from two samples in order to obtain a "pooled variance estimate"? (1 pt)

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  5. What information does eta2 provide? (1 pt)

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  6. When do we conduct an independent groups t-test? (½ pt)

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  7. Air Force psychologists are conducting research into the relative effectiveness of two

methods of training navigators. The first method makes use of computer-simulated flights, the second uses traditional classroom instruction. A random sample of 32 navigators-in-training is observed and 16 navigators are randomly assigned to each method. After completing the respective training methods, both groups perform the same assessment test. Group 1 (computer training) received a mean of 8.2 with an estimated standard deviation of 1.893. Group 2 (traditional training) received a mean of 6.2 with an estimated standard deviation of 1.159. Determine if there is a statistically significant difference between training methods. (assume alpha = .05, non-directional test).

a) Identify your independent and dependent variables. (1 pt)

b) What are your formal hypotheses? (½ pt)

c) What are your degrees of freedom (df) and critical t value? (½ pt)

d) Compute the estimated standard error of the difference between means. (2 pts)

 

 

 

e) Compute the test statistic (independent groups t test). (1 pt)

 

f) What is your decision? (½ pt)

g) How strong is the relationship between the IV and DV? (1 pt)

 

 

h) Describe the nature of the relationship. (½ pt)