Symptom-Checklist-K-9: Norm values and factorial structure in a representative German sample

BACKGROUND: The SCL-K-9 is the latest short version of the multidimensional Symptom-Checklist 90-R. Up to now, its psychometric properties have not been clarified sufficiently as the nine items have not yet been presented exclusively in a representative sample. Therefore, psychometric properties, model fit values as well as norm-values were analyzed. METHODS: For the sample, N = 2,507 participants aged 14 to 92, n = 1,379 women and n = 1,128 men, and a mean age of 48.79 (SD = 17.91), were selected from the general population by random-route sampling. Confirmatory factor analyses applying full information maximum likelihood (FIML) tested the model fit. The reliability estimations and effect sizes were reported. RESULTS: The items’ discriminative power ranged between .49 to .65, and the Cronbach’s Alpha was α = .87, which stands for a good reliability of the SCL-K-9. Norm values as well as gender and age specificities were presented in this section. The CFA with all nine items loading on one latent factor resulted in a good fit. There was evidence of invariance across age and gender groups. SUMMARY: Based on these results, the short screening version SCL-K-9 of the Symptom-Checklist 90-R showed good reliability and good model fit; specific norm values could be determined. Further studies should evaluate the usefulness of the standardization in clinical samples.