# Lesson 10 1. A researcher using an independent-measures design to compare two treatments obtained...

Lesson 10

1. A researcher using an independent-measures design to compare two treatments obtained the following data:

______________________________

___Treatment 1_____Treatment_2__

n = 16 n = 16

M = 58 M = 52

SS = 420 SS = 540

______________________________

a. Calculate the variance for each of the two samples and then compute the pooled Variance.

b. Do these data indicate a significant difference between the two treatments? Use a Two-tailed test with α = .05.

2. Stephen Schmidt (1994) conducted a series of experiments examining the effects of humor on memory. He collected a set of humorous sentences and then modified each one to produce a nonhumorous version of the same sentence. The humorous sentences were then presented to one group of participants and the nonhumorous sentences were presented to another group. Each group was then given a test to determine how many sentences they could recall. Data similar to those obtained by Schmidt are shown in the following table.

____Number of_Sentences_Recalled___

Humorous Nonhumorous

__sentences______________sentences__

4 5 2 4 5 2 4 2

6 7 6 6 2 3 1 5

2 5 4 3 3 2 3 3

3 3 5 3 4 1 5 3

__________________________________

a. Do the data provide enough evidence to conclude that humor has a significant effect on memory? Use a two-tailed test at the .05 level of significance.

b. Calculate Cohen’s d to evaluate the size of the effect.

c. Calculate the percentage of variance explained the treatment, r2, to measure effect size.

1. A researcher using an independent-measures design to compare two treatments obtained the following data:

______________________________

___Treatment 1_____Treatment_2__

n = 16 n = 16

M = 58 M = 52

SS = 420 SS = 540

______________________________

a. Calculate the variance for each of the two samples and then compute the pooled Variance.

b. Do these data indicate a significant difference between the two treatments? Use a Two-tailed test with α = .05.

2. Stephen Schmidt (1994) conducted a series of experiments examining the effects of humor on memory. He collected a set of humorous sentences and then modified each one to produce a nonhumorous version of the same sentence. The humorous sentences were then presented to one group of participants and the nonhumorous sentences were presented to another group. Each group was then given a test to determine how many sentences they could recall. Data similar to those obtained by Schmidt are shown in the following table.

____Number of_Sentences_Recalled___

Humorous Nonhumorous

__sentences______________sentences__

4 5 2 4 5 2 4 2

6 7 6 6 2 3 1 5

2 5 4 3 3 2 3 3

3 3 5 3 4 1 5 3

__________________________________

a. Do the data provide enough evidence to conclude that humor has a significant effect on memory? Use a two-tailed test at the .05 level of significance.

b. Calculate Cohen’s d to evaluate the size of the effect.

c. Calculate the percentage of variance explained the treatment, r2, to measure effect size.

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