Usually reliability is measured for factual questions. However in KAP questionnaires where the knowledge, attitude and practice of a person is usually dynamic and can change over a period of time. How can we test the validity and reliability of the questionnaire?
Both reliability and validity are usually tested via correlations, so if both of the variables in a correlation change in the same direction (i.e. they each increase), then the correlation can remain the same. Thus, measures of reliability and validity can be high at both periods in time, even the underlying scores change.
Reliability is a measure of the consistency of response to a questionnaire and, as David says, is usually measured by correlation. Conventionally, three types of reliability are usually assessed:
Test-retest reliability; is the test consistent over time. get the group to take the test, wait awhile, get them to take the test again, correlate the two sets of scores.
Alternate form reliability: if there are two versions of the questionnaire, do they measure the same thing? Get a group top take both versions, and correlate the results
Internal consistency reliability: do all the items in the test measure the same thing? Get a group to take the test, then score up two halves of the test separately, then correlate these scores (split half reliability) or use more sophisticated methods such as coefficient Alpha.
In your case, test-retest reliability may not be appropriate but the other forms should be.
It depends on the items within the KAP questionnaire. If items are in a likert scale format, then cronbach's alpha for reliability can be done. regarding validity, mostly it will be acceptable with content validity with a panel of expert [make sure they are expert in the field with significant publications and experience].
however, if the scales don't look like likert, and with different levels of measurement, mostly the study will be just descriptive {incidence, with means and SD..frequencies..} then, reliability test is not within the scope
Dear Researcher
1. The concepts:
The concepts and measures of reliability and validity play an important role in many social and applied sciences and are widely applied in psychology and education. In the theory of reliability, there are many forms/categories of reliability measures, each of which has a different concept, meaning and estimates.
2. For more details, please refer to:
1. Z. A. Al-Hemyari and A. M. Al-Sarmi (2016). Validity and Reliability of Students and Academic Staff’s Surveys to Improve Higher Education. Educational Alternatives, Journal of International Scientific Publications, Vol.14, pp. 242-263
2- A. M. Al-Sarmi and Z. A. Al-Hemyari (2014). Quantitative and qualitative indicators to assess
the performance of higher education institutions. Int. J. of Information and Decision sciences,
Vol.6, No. 4, pp.369-392 (Inderscience).
3- Z. A. Al-Hemyari and A. M. Al-Sarmi (2014). Statistical characteristics of performance indicators. Int. J. of Quality and Innovation. Vol.2, No.3-4, pp. 385-309 (Inderscience).
Regards,
Zuhair
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