A difficult nexus can arise in positivist research when developing a model or theoretical framework that is then used to underpin the construction of measuring instruments that are subsequently used to test the assumptions underlying the model. This paper explores this nexus through consideration of a study of risk-taking in decision-making for public school principals in Western Australia (WA). A theoretical model of factors impacting on reasoned risk-taking in decision-making was developed and a questionnaire developed to measure the constructs included in the research model as there were no pre-established measurement instruments. The design of the questionnaire and development of items utilised findings from research in measurement theory to structure the items and the response scales to measure constructs in the model. Data was provided from a stratified random sample of principals in 253 schools. Rasch modeling and factor analysis were used to analyse the resultant measurement scale.