Validity and reliability of self-initiated professional development (SI-PD) instrument: a rasch measurement model approach for pilot study

Abstract

This pilot study was conducted to generate empirical evidence on the validity and reliability of elements of Self-Initiated Professional Development (SI-PD) for TVET teachers’ in vocational colleges. Construct validity was used by analyzing point-measure correlation index (PTMEA CORR), infit and outfit MNSQ values, standard residual correlations, item reliability and person reliability. The instrument was distributed to 40 TVET teachers in Malaysian vocational colleges. This instrument was developed to measure ten SI-PD elements, namely, Understanding, Rewards, School Administrators’ Role, Professional Development System, Attitude, Readiness, Collaborative Environment, Industrial Attachment Opportunity, Autonomy and Strategy. The reliability value based on Alpha Cronbach value was 0.98 which indicated that the instrument was very good and effective with high degree of consistency. The person reliability value was 0.97 while the item reliability value was 0.86. This indicated that the respondents selected were highly reliable because the value were more than 0.80. The separation index value for respondents was 5.68 which indicated that there were six groups levels in giving agreement on SI-PD elements, while, item separation index of 2.46 indicated there were three levels of item difficulty. Removing and refining the items was done by taking account supervisors’ and experts’ views and evaluation. This pilot study showed that only five items did not meet the criteria and 76 items remained to be used for actual study. In conclusion, findings from the study clearly showed that the developed instrument have a high level of validity and reliability and capable to be used in measuring SI-PD elements.