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

OBJECTIVE: To examine the structure of the sense of coherence (SOC) scale in a general population.
METHODS: 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.
RESULTS: 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.
CONCLUSION: 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.