Clinical Psychology

things can only be studied by observing their occur-

rences; creating them is notan acceptable alternative.

Factor Analysis. Derived from the correlational

strategy,factor analysisis a way of examining the

interrelationships among a number of variables at

the same time. This statistical method uses many

separate correlations to determine which variables

change in concert and, thus, can be considered

functionally related. The idea is that when variables

change together, they must have some element in

common that underlies their relationship.

Consider the following example. Suppose we

are trying to identify the basic elements of what is

called“clinical skill.”First, we ask a panel of judges

to select 100 clinicians who are known to have

excellent records in providing skilled services.

Then, we administer a large number of tests that

35

30

25

20

15

10

5

1 2 3 4 5 6 7

Test X

r = +1.00

Perfect

Test Y

35

30

25

20

15

10

5

1 2 3 4 5 6 7

Test X

r = –.67

Moderate

Test Y

35

30

25

20

15

10

5

1 2 3 4 5 6 7

Test X

r = .00

Unrelated

Test Y

F I G U R E 4-2 Scatterplots showing several different magnitudes of relationships.

104 CHAPTER 4