PSYCHOTHERAPY ENGAGERS VERSUS NON-ENGAGERS
PSYCHOTHERAPY ENGAGERS VERSUS NON-ENGAGERS
PSYCHOTHERAPY ENGAGERS VERSUS NON-ENGAGERS
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Chapter 4: Method<br />
The present study examined therapist helping skills across thirds of intake<br />
sessions (1 st , 2 nd , and 3 rd thirds) and across engagement condition (engager vs. non-<br />
engager). The design of the present study is a quantitative descriptive field design.<br />
Power Analyses<br />
Power analyses for 2-tailed t-tests indicated that for a large effect size, d = 0.8, at<br />
an alpha level of .05, 52 participants (26 engagers, 26 non-engagers) would be needed for<br />
80% power. With the same expected effect size, d = 0.8, and same power level of 80%,<br />
but changing the alpha level to .10, 40 clients (20 engagers, 20 non-engagers) would be<br />
needed. With the same effect size of .8 and power of 80%, but an alpha of .20, 30 clients<br />
would be needed (15 engagers, 15 non-engagers). Effect sizes from Tryon (2003)<br />
indicated very large effects for closed questions, d = 2.86, and information, d = 3.29.<br />
Using the effect size d = 2.86, and alpha = .10, 6 clients (3 engagers, 3 non-engagers)<br />
would be needed to have 80% power. Using the effect size d = 3.29, and alpha = .10, 6<br />
clients (3 engagers, 3 non-engagers) would be needed to have 80% power. The present<br />
study, with 8 dropouts and 8 continuers, has 84.5% power to detect effects of d = 1.4 at<br />
an alpha level of .10 when such effects indeed exist. Thus, the present sample size<br />
provides sufficient power for detecting very large effects (d = 1.4) at alpha levels of .10.<br />
Participants and Setting<br />
Setting. The present study utilized data collected in the Maryland Psychotherapy<br />
Clinic and Research Lab (MPCRL), a mental health clinic providing individual<br />
psychodynamic/interpersonal psychotherapy to adults from the local community. One of<br />
the main purposes of the clinic was to collect data for psychotherapy research; thus, all<br />
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