DrMKZ

 Cronbach’s α coefficient of 0.839, which reflects strong internal reliability. Additionally, confirmatory factor analysis (CFA) was performed to evaluate construct validity.

Reliability = “Is the questionnaire consistent?”

Reliability tells us whether the questions that are supposed to measure the same thing give consistent results.

For example, if you have 5 questions measuring knowledge of cardiovascular disease, people who score high on one relevant question should generally score high on the others.

The most common test is Cronbach’s α (alpha).

Validity = “Is the questionnaire measuring what it is supposed to measure?”

A questionnaire can be very consistent but still measure the wrong thing.

For example, imagine a questionnaire intended to measure cardiovascular disease knowledge, but most questions actually measure people’s attitudes. It could be reliable but not valid.

There are several types of validity:

Content validity
→ Are the questions appropriate and cover the important areas?

Example: Cardiovascular KAP questionnaire should cover risk factors, symptoms, prevention, treatment, etc.

Construct validity
→ Do the questions actually represent the underlying concepts they are supposed to measure?

One way to test this is factor analysis.

Confirmatory factor analysis (CFA)
→ You already have an expected structure and test whether your questionnaire fits that structure.

For example:

Knowledge → questions 1–10
Attitude → questions 11–18
Practice → questions 19–25

CFA asks:

“Does the actual data support this KAP structure?

Reliability and Validity.

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