Structure of the sense of coherence scale in a nationally representative sample: the Finnish Health 2000 survey

To examine the structure of the sense of coherence (SOC) scale in a general population. This study analysed the responses of 6,217 subjects aged 30 years and over who participated in the Finnish Health 2000 survey (response rate 77.4%). Participants completed an abbreviated 12-item version of the SOC scale. Two alternative structures were tested using confirmatory factor analysis: a one-factor model, with all scale items loaded onto a single latent factor representing the SOC construct, versus a second-order factor model, with scale items loaded onto their corresponding latent factors representing the three SOC components (comprehensibility, manageability and meaningfulness), which are, in turn, dependent on one single higher-order SOC construct. The one-factor model was fitted to the data after allowing the errors of comprehensibility item 5 and manageability item 6 to correlate, as was done in previous studies among Finnish adults. The comparative fit index (CFI), Tucker-Lewis index (TLI) and root mean square error of approximation (RMSEA) for the one-factor model were, respectively, 0.97-0.98, 0.96-0.97 and 0.05-0.09 across both sexes and three age groups. The second-order factor model had correlations between latent factors higher than 1, even after alternative model modifications, casting doubts on this more complex structure. These data suggest that the components of comprehensibility, manageability and meaningfulness should be merged when measuring SOC with the 12-item SOC scale in the Finnish general population.