You said "before going to data collection", meaning you probably have a questionnaire at hand. One easy way to determine if the questionnaire is reliable and valid is to search the literature and see if the said questionnaire has already been validated in your intended population or country.

If not, then you have to pretest the questionnaire in a sample (at least 30, but the more the better) drawn from the population of interest. Administer the questionnaire to them, as you would in your intended "data collection" method.

Determine the Cronbach's alpha for reliability (target is >=0.70 score). Validity can be determined by a wide range of tests such as thr discriminant validity, convergent validity and construct validity. [You probably should not worry about these tests at this point...Get on with the pretest first, then ask how to do these tests later on.]

Hope this helps! Good luck!

Dear Phani,

What help do you need? Would you like to validate a questionnaire? Or use an established validated one?

Reliability can be tested through Cronbach Alpha.

You said "before going to data collection", meaning you probably have a questionnaire at hand. One easy way to determine if the questionnaire is reliable and valid is to search the literature and see if the said questionnaire has already been validated in your intended population or country.

If not, then you have to pretest the questionnaire in a sample (at least 30, but the more the better) drawn from the population of interest. Administer the questionnaire to them, as you would in your intended "data collection" method.

Determine the Cronbach's alpha for reliability (target is >=0.70 score). Validity can be determined by a wide range of tests such as thr discriminant validity, convergent validity and construct validity. [You probably should not worry about these tests at this point...Get on with the pretest first, then ask how to do these tests later on.]

Hope this helps! Good luck!

Agree with Mohammed! Would like to add a bit more that generally two types of validity in quantitative research- (i) internal validity: that indicates how accurately questionnaire is made by right items or questions, (ii) external validity that we usually called generalizability: that represents how we can use findings from one context to another.

Reliability- once you you have data in your hand you may determine reliability by Cronbach's Alpha. If the Cronbach's Alpha is > 0.7, the consistency and precision of the data is quite ok.

Thanks Mohammed M. Alhaji sir for your explanation.

Kurubaran Ganasegeran sir,

As per for my proposed e-loyalty model i have taken existing questionnaire from previous studies, apart from 2 variables which i want to study.

Thanks for your concern

my doubt is that is it necessary to test the questionnaire before going to collect data.