Dear Lwin,

This question was asked two years ago and you can benefit from the answers that were given then! Good luck,

Rachel.

https://www.researchgate.net/post/What_is_the_sample_size_required_for_a_questionnaire_validation2

Dear Lwin

1. Validity may be defined by the scales of measurement should measure what it claims to measure and is not confounded by other factors.

2. In order to assure the validity of the scale used, an old survey or a modified research instrument may be used in your research.

3. I recommended the answer given by Rachel.

Regards,

Zuhair

The 100(1-alpha)% confidence interval for the mean is given by xbar(+/-)(zalpha/2)*sigma/√n. It follows that the error margin e=(zalpha/2)*sigma/√n. Therefore n > =[( zalpha/2)*sigma]^2/e*e. This means that the sample size n is a function of the error margin e, the level, alpha, of significance and the data variance sigma. Therefore the less alpha is, the more n should be. The less the error e, the more n should be. The more sigma, the more n should be.