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# Hypothesis Testing, Cohen's d & Effect Size

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1. One sample has SS= 35 and the second sample has SS=45.
a) assume that n=6 for both, calculate the sample variance, and the pooled variance.
b) assume that n=6 for one and n=16 for the other, calculate the two sample variances and the pooled variance.

2. A sample of n=10 people receive medication with pain tolerance and n=10 for people who received a placebo. The score for the placebo group produce a mean of M=38 with SS=150
a) if the score for the medication group have a mean of M=42 with SS= 210, are the data sufficient to conclude that the medication has a significant effect? Use a two tailed test with &#945;= .05
b) the medication group averaged 4 points higher than the controlled group.If the effect was 8 points, so the medication group had a mean of M=46 with SS=210 would the data be sufficient to conclude that there is a signficant effect? Use a two tailed test with &#945;= .05

3. Number of Sentences Recalled
Humorus Sentences Nonhumorus 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 .05 level of significance.
b) Calculate Cohen's d to evaluate the size of the effect.
c) Calulate the precentage of variance explained by the treatment, r2, to measure the effect size.

4) A researcher conducts an independent-measure research study and obtains t=2.070 with df= 28.
a) How many individuals participated in the entire research study?
b) Use a two-tailed test with &#945;=.05, is there a significant difference between the two treatment conditions?
c) Compute r2 to measure the percentage of variance accounted for by the treatment effect.