Q1) Independent-Samples
t
Test
(Round calculated results to the hundredth (2
nd
place to the right of the decimal))
In a cognitive psychology experiment, the researcher is interested in whether encoding condition has a significant effect on memory for a set of drawings. In encoding condition A, subjects are asked to name the object in each drawing; in encoding condition B, subjects are asked to name the color of each drawing. Then all subjects are tested on their memory of the drawings. Each recruited subject is randomly assigned to either encoding condition A or encoding condition B.
Based on memory theories, the researcher hypothesized that condition A (object naming) would lead to significantly better memory compared to condition B (color naming), and she sets the significance level at α = .05 for a one-tailed test.
Hint: You may remember a similar scenario in the previous assignment, but with a crucial difference. In the previous assignment, each subject is tested in BOTH condition A and condition B, while each subject here is tested in only ONE condition (either A or B).
Subject ID
|
Encoding A
|
|
Subject ID
|
Encoding B
|
1
|
86
|
|
13
|
90
|
2
|
76
|
|
14
|
85
|
3
|
94
|
|
15
|
81
|
4
|
90
|
|
16
|
76
|
5
|
80
|
|
17
|
73
|
6
|
89
|
|
18
|
83
|
7
|
78
|
|
19
|
79
|
8
|
83
|
|
20
|
75
|
9
|
89
|
|
21
|
87
|
10
|
91
|
|
22
|
88
|
11
|
78
|
|
23
|
84
|
12
|
83
|
|
24
|
86
|
F. Calculate the pooled variance (S
pooled2
)from the two population variances (from question e above)
G. Use the pooled variance (from question f above) to calculate the variance for sampling distribution 1 (S
M12) and the variance for sampling distribution 2 (S
M22)
Hint: Sampling distribution is derived from the original population and it consists of means of all possible samples drawn from the original population.
H. Calculate standard deviation (S
diffmean)of the comparison distribution
Hint: This comparison distribution consists of differences between all possible sample means drawn from the two sampling distributions. Its standard deviation is the denominator of the t statistic formula.
I. Calculate thetstatistic