A researcher is examining whether affirmations improve productivity. The researcher assigns n = 12 individuals to perform affirmations for three months and finds an average productivity score of M = 25 with SS = 120 after three months for individuals in this group. A second group of n = 12 individuals assigned to a control group for the three months has a productivity score of M = 30 with SS = 100.

Compute the test statistic for a two-tailed independent-measures t test with = .05

Group of answer choices

-1.88

3.02

-3.87

0.34

A researcher conducts an independent-measures study examining the effectiveness of an afterschool program on attention in children. One group of children is selected to participate in the program, and a second group serves as a control. After 6 weeks, the researcher records a score measuring attentional ability for each individual.

The data for the afterschool program participants is as follows: n=12, M=24, SS=170.

For the control participants the data is as follows: n=12, M=20, SS=160.

Determine whether the program has a significant effect on attention and compute Cohen's d. Use an alpha level of .05, two tails.

Group of answer choices

The program does not have a significant effect on attention and d=1.03

There is not enough information in the problem to determine whether the program has a significant effect

The program has a significant effect on attention and d=1.03

The program has a significant effect on attention and d=2.29

A set of n = 17 difference scores has a mean of MD = 3 and SS = 64. What is the Cohen's d for this data? Group of answer choices

1.50

0.17

1.00

0.55