"This paper discusses how methodological challenges and problems were handled in a study of how state employees' unions responded to, had an impact on and were affected by new public management reforms in Sweden, Norway, Australia and New Zealand. In the study, particular emphasis was put on institutional characteristics of the unions. The paper clarifies the operational measures of this concept (construct validity) and their causal relationship to the actions and outcomes of the reform processes (internal validity). Two other aspects of research design (external validity and reliability) are also discussed. Finally, some more general lessons learned from the study are indicated."

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