[Additional psychometric data for the DS1K mood questionnaire. Experience from a large sample study involving parents...

A new instrument for assessing depressive mood, the first version of Depression Scale Questionnaire (DS1K) was published in 2008 by Halmai et al. This scale was used in our large sample study, in the framework of the For Healthy Offspring project, involving parents of young children. The original questionnaire was developed in small samples, so our aim was to assist further development of the instrument by the psychometric analysis of the data in our large sample (n=1164).

The DS1K scale was chosen to measure the parents' mood and mental state in the For Healthy Offspring project. The questionnaire was completed by 1063 mothers and 328 fathers, yielding a heterogenous sample with respect to age and socio-demographic status. Analyses included main descriptive statistics, establishing the scales' inner consistency and some comparisons. Results were checked in our original and multiple imputed datasets as well.

According to our results the reliability of our scale was much worse than in the original study (Cronbach alpha: 0.61 versus 0.88). During the detailed item-analysis it became clear that two items contributed to the observed decreased coherence. We assumed a problem related to misreading in case of one of these items. This assumption was checked by cross-analysis by the assumed reading level. According to our results the reliability of the scale was increased in both the lower and higher education level groups if we did not include one or both of these problematic items. However, as the number of items decreased, the relative sensitivity of the scale was also reduced, with fewer persons categorized in the risk group compared to the original scale.

We suggest for the authors as an alternative solution to redefine the problematic items and retest the reliability of the measurement in a sample with diverse socio-demographic characteristics.