Development of a Quality Measure for Adults with Post-Traumatic Stress Disorder. B. Exploratory Factor Analysis

05/01/2019

To identify the underlying factor structure of the survey, we fit a series of EFA models with varying numbers of latent factors (5, 6, 7, and 8). We examined the models' statistical fit and how well they corresponded to our theoretical understanding of the underlying constructs of evidence-based psychotherapy for PTSD.

According to the model fit statistics (Appendix H, Table H.1), all four of the EFA models represented the underlying data structure very well, suggesting that from a statistical standpoint any of these models could inform the CFA. We then examined the factor structures for parsimony and clinical meaning. The five-factor model provided the most parsimonious solution with the least number of significant cross-loadings. This solution was also the most interpretable based on constructs identified during the measure development stage. For these reasons, we retained the five-factor model (see Table V.2) for further validation at the CFA stage.

In grouping items into factors, we considered items with factor scores of 0.40 or above. If an item cross-loaded on multiple factors, we assigned it to the factor where it had the highest loading and/or for which other factors related to the item also scored highly. Below, we describe the factor groupings and the labels we assigned to each factor.

  • Factor 1: Structuring and conducting the therapy session. Ten items compose Factor 1 and include aspects of treatment such as creating an agenda, setting treatment goals with the client, soliciting client feedback on treatment, and being directive.

  • Factor 2: Psychoeducation and therapeutic techniques. Fifteen items make up Factor 2. The majority of items are therapeutic techniques (that is, cognitive restructuring, Socratic method, imagining the traumatic event) and psychoeducation (providing education about symptoms and/or the traumatic event).

  • Factor 3: Therapeutic alliance. Three items from the therapeutic alliance measure make up Factor 3.

  • Factor 4: Assessment. Two items on assessment loaded on this factor.

  • Factor 5: Homework. All six of the items that loaded on this factor are related to assigning, reviewing, and encouraging homework completion.

Five items were not statistically significantly associated with any of the factors. These items included the suicide risk assessment questions, use of Socratic questioning, the facilitation of alternate hypotheses, and one question on the clinician's time management.

TABLE V.2. The Five-Factor EFA Solution
Clinician Survey Item Number Factor 1 Factor 2 Factor 3 Factor 4 Factor 5
12.a. IMAGINE   0.699*      
12.b. WRITE   0.783*      
12.c. OTHER SOCRAT -0.266* 0.867*      
12.d. REAL   0.578*      
26. TRUST     0.750*    
24. CONFIDENT     0.774*    
25. LIKES     0.818*    
1. AGENDA 0.790*        
2. REVIEW AGENDA 0.719* 0.376*   -0.290*  
3. BACKGROUND 0.307* 0.676*      
4. EXPECTATIONS 0.696*        
5. GOALS 0.647*        
10. IDENTIFY   0.670*      
7. COG RESTRUC   0.469*      
8. SOCRAT          
9. FACILITATE          
10. OTHER IDENTIFY   0.556*      
11. TECHNIQUES   0.633*      
13. DISCUSS 0.226* 0.549*      
14. STRUGGLE          
15. DIRECTIVE 0.853*        
16. TX FEEDBACK 0.604* 0.233*      
17. TH FEEDBACK 0.431*        
18. ASSIGN         0.769*
19. REVIEW INSTRUC         0.722*
20. ADDRESS         0.949*
21. SOLUTION         0.749*
22. REVIEW HMWK         0.925*
23. ENCOURAGE         0.874*
27.a. EVER SUIC          
27.b. TODAY SUIC 0.269*        
28.a. EVER USE SUIC          
28.b. TODAY USE SUIC          
29.a. EVER INSTRU       0.614*  
29.b. TODAY INSTRU 0.466*     0.750*  
30.a. EVER SYMP EDU   0.699*   -0.393*  
30.b. TODAY SYMP EDU   0.836*      
31.a. EVER TRAUMA ED   0.574*      
31.b. TODAY TRAUMA ED   0.768*     -0.254*
32.a. EVER OUTLINE 0.516*        
32.b. TODAY OUTLINE 0.685* 0.369*      
12. OVERALL TECHNIQUES   0.737*      
* Factor loadings not significant at p < 0.05 were excluded from the table to facilitate interpretation of the results.