A valid questionnaire must have following characteristics (1) reliability and precision in the words; (2) simplicity and
viability; (3) reflect underlying theory or concept to be measured; (4) adequate for the problem
intended to measure and (5) capable of measuring change (García et al., 2008).
One widely used method of measuring content validity was developed by (Lawshe, 1975). It
is essentially a method for gauging agreement among raters or judges regarding how essential a
particular item is. Lawshe (1975) proposed that each of the subject matter expert raters (SMEs)
on the judging panel respond to the following question for each item: Is the skill or knowledge
measured by this item 'essential,' 'useful, but not essential,' or 'not necessary' to the performance
of the construct? Referring to Lawshe (1975), if more than half the panelists indicate that an item
is essential, that item has at least some content validity. Greater levels of content validity exist as
larger numbers of panelists agree that a particular item is essential. Using these assumptions,
Lawshe developed a formula termed the content validity ratio: