Validity and reliability of Islamic spiritual wellbeing index for adolescent (IKSIR) using rasch analysis

The aim of this study was to examine the degree of validity and reliability of a new developed instrument. The instrument was developed to measure the level of spiritual well-being among Muslim adolescence in Malaysia. Throughout this study, the empirical evidence of validity and reliability of this instrument by using Rasch Model was discussed. The instrument measure the level of spiritual well-being by four constructs which are faith, knowledge, worship and morals. A survey was conducted to 298 form four students from three Islamic based secondary schools in Johor. Statistical analysis using Winsteps software was performed to measure the validity and reliability of 71 items in the instrument. Results showed the reliability of the IKSIR items are between 0.93 to 0.99. The separation index of item was above 2; all items indicated positive value in polarity item analysis while six items were identified with the value of MNSQ infit and outfit beyond the standardized range of 0.5 to 1.5 should be dropped from the instrument. Thus, the degree of validity and reliability of IKSIR were high according to the Rasch model of measurement