Do different scales measure the same construct? Three Sense of Coherence scales.

In English Background: Different scales claim to measure the
construct ‘‘Sense of Coherence’’. Results from these
scales have been compared without knowing whether
they measure the same construct. This article compares
two versions of Antonovsky’s original scale (SOC-13 and
SOC-29), translated into Swedish, and a three-item scale
(SOC-3) that claims to measure Sense of Coherence.

Methods: The data were analysed in a cross-sectional
setting. The study consisted of university students
studying social work (n=395.

Results: The original scales had no distribution problems
in differentiating Sense of Coherence. The SOC-3 had
severe distribution problems. The two versions of the
original Sense of Coherence scale had an acceptable
reliability (Cronbach’s a; SOC-29=0.93, SOC-13=0.89).
The SOC-3 scale did not have an acceptable reliability
(Cronbach’s a=0.39). SOC-29 and SOC-13 had a high
intercorrelation (r=0.96, p,0.001). The SOC-3 significantly
correlated with SOC-29 (r=20.72, p,0.001) and
SOC-13 (r=20.67, p,0.001), but the magnitude was
significantly lower than the intercorrelation between SOC-
29 and SOC-13 (Fisher’s z-transformation, p,0.001.

Conclusions: Because scales that claim to measure the
same construct are not always interchangeable,
researchers should make sure they compare results from
studies that use the same scales.