Ruler & option scale: development of an interval measurement technique / Rohana Yusoff

Motivated by the on-going debate between researchers on whether data from rating scales such as Likert and Likert-type scales are ordinal or interval level, this research had set out to grasp the actual problems that fuelled the debate. The problems are threefold i) the absence of a rating scale that is unanimously accepted by all researchers as interval level, ii) unclear definition of an interval rating scale, and iii) no comprehensive method to establish a rating scale as an interval scale. These are the research gaps this research identified. Research objectives was fourfold, i) to identify the features of a rating scale that could be accepted as interval level, to design the layout, and to name the scale as Ruler & Option (RO) scale, ii) to determine the usability of RO scale and its consistency compared to 7-point Likert scale, iii) to compare validity and reliability coefficients of data collected using RO scale with the validity and reliability coefficients of data collected using 7-point Likert scale, and iv) to establish RO scale is interval conceptually and mathematically by giving a clear definition of an interval scale and to examine the interval property of RO scale using Rasch model and Double Cancellation axiom.