Traditionally, measurement indicators could be categorized as being objective and subjective .
Objective indicators generally refer to quantitative data and the majority of them could be described through various equations.
Subjective indicators are based on personal feeling and attitude, and are usually qualitative in nature.
Objective indicators have been widely used because these were seen as more rigorous. However, Schneider and Donaghy () argued, the use of objective measures alone as quality of life indicators is highly suspect.
WTO () reveals the true position of qualitative measures,