Validity of the standard shiftwork index for South African shiftworkers in the transport industry

Abstract

A major problem in shiftwork research has been the lack of uniform measuring procedures across studies. The Standard Shiftwork Index (SSI) contains a battery of self-report questionnaires which was developed to address this need. The objectives of this study included examining the cross- cultural applicability, internal consistency, and construct validity of the SSI scales for a predominantly Afrikaans-speaking sample of 728 train drivers and to provide normative distribution statistics for this sample. Factor analytic results and the correlations between the various scales supported the constnuct validity of the SSI scales. Means obtained on the scales were compared with means obtained for British shiftworkers and non-shiftworkers. The inclusion of job satisfaction and involvement scales, and scales to assess sleep variables appeared to augment an outcome- based theoretical model proposed by the compilers of the SSI. It was concluded that the SSI is a useful research tool for use with shiftworkers, but that further development of some of the scales is advisable.

Opsomming
'n Belangrike leemte in navorsing oor skofwerk is die gebrek aan eenvormige metingsprosedures. Die Standard Shiftwork Index (SSI) behels verskeie selfbeoordelingvraelyste wat in Engeland ontwikkel is om hierdie behoefte aan te spreek. Die doelwitte van hierdie studie was om die tussenkulturele toepaslikheid, interne konsekwentheid en konstrukgeldigheid van die SSI-skale vir 'n hoofsaaklik Afrikaanssprekende steekproef van 728 treindrywers te bepaal en om normatiewe statistiek vir hierdie steekproef te verskaf. Faktoranalitiese resultate en die korrelasies tussen die onderskeie skale het hul konstrukgeldigheid ondersteun. Gemiddeldes wat op die onderskeie vraelyste behaal is, is vergelyk met gemiddeldes wat vir Britse skofwerkers en nieskofwerkers verkry is. Die insluiting van werktevredenheid- en werkbetrokkenheidskale, asook skale oor slaap, het die uitkomsgebaseerde teoretiese model van die opstellers van die SSI aangevul. Die SSI kan beskou word as 'n nuttige navorsingshulpmiddel vir gebruik met skofwerkers, maar verdere ontwikkeling van sommige van die skale is gewens.