Question

Extern.	Anxiety
2	26
3	21
6	23
6	33
6	35
7	23
7	26
9	28
9	37
11	42

1.)A correlational analysis can be calculated as the pattern of how the two variables change in value. Because the two variables are on different measurements, the scores need to be converted into Z scores so the variables can be examined together. To calculate Z scores, we need the mean and standard deviation for each variable. Using the data in the previous question, enter the standard deviation for externalizing behavior. (Round the answer to 2 decimal places)

2.)Calculate the correlation coefficient r value using the Z scores for the two variables. (Round the answer to 2 decimal places)

Answer 1

(1) We input the data set in MS Excel and use the AVERAGE and STDEV functions to calculate the mean and the standard deviation and then use them to calculate the z-score using the formula "(original score - mean)/standard deviation".
For externalizing behaviour, we get mean = 6.6, standard deviation = 2.72.
For anxiety, we get mean = 29.4, standard deviation = 6.98.

(2) The table containing the z-scores is given below.

Extern.	Anxiety	z-score (Extern.)	z-score (Anxiety)
2	26	-1.69	-0.49
3	21	-1.33	-1.20
6	23	-0.22	-0.92
6	33	-0.22	0.52
6	35	-0.22	0.80
7	23	0.15	-0.92
7	26	0.15	-0.49
9	28	0.88	-0.20
9	37	0.88	1.09
11	42	1.62	1.81

We use the CORREL function in MS Excel to calculate the correlation coefficient using the z-scores for the two variables and it is equal to 0.65.