Profiling Willingness to Advocate Water Conservation Behaviour: Item Validation using Rasch Measurement Model

摘要

The reliability and validity of questionnaire items is the first step toward accepting them as a valid measurement instrument. This paper investigates the validity of 23 items in a questionnaire used to profile the willingness to advocate water conservation behaviour (WCB) among ESL teachers in HEIs in Selangor. One hundred and sixty two questionnaires were analysed using several tests in Rasch Measurement Model to validate the items. It was found that items could not separate person sufficiently but reliability of 0.97 deemed it fit for further analysis. The items were tested for item fit, unidimcnsionality, differential item functioning, and rating scale validation. The vigorous tests show that items are valid, hence its poor ability to separate person adequately could be due to low quality of item construction. From the analysis, a person-item scale was produced. This validation process is essential before profile of water conservation behaviour advocates could be developed.