1. The meaning of Reliability and Validity in psychological research

2. Imagine that you’ve produced a new test which measures people’s reading ability but each time you take the test it gives different results, or you get one score when I mark the test but a completely different score when another person marks it! These scores are clearly not very
______________?
This means your new reading test isn’t any good!

3. Answer = Reliable
Clearly if the results are inconsistent then they cannot be relied on because they are not trustworthy.
Psychologists would say these results lack ‘reliability’.

4. In order to conduct research, psychologists must find ways of measuring things.
Many instruments of measurement we are already familiar with like bathroom scales, rulers, speedometers etc.

5. But for these things to be useful we need to be able to trust them!
They must measure what we want them to measure and they must be consistent, in other words you should measure the same height wherever and whenever you measure yourself –provided your tape measure is reliable that is!

6. Reliability refers to the consistency of a measuring instrument.
If a measurement is reliable it will be consistent and stable.
If a measurement is reliable we can trust the results.

7. Or have you measured something else instead?
Validity
The validity of a psychological measure is the extent to which it measures what it is intended to measure –
Or have you measured something else instead?

8. If you can think of any other possible explanation for your findings then it could be that your research isn’t valid.
For example does an IQ test actually tell us how intelligent a person is? Or is it actually measuring something else? Like how well a person can read English or how good their general knowledge is.
If an IQ test doesn’t actually measure INTELLIGENCE then it is not VALID.

9. A tape measure may be a reliable measurement tool – but if we were using it to measure the circumference of peoples’ heads as a way of measuring intelligence it wouldn’t be very valid!

10. Check your understanding
The extent to which a test measures what was intended is known as what?

11. Answer: Validity

12. Valid Consistent Meaningful Useful
Reliability means the measurement is?
Valid
Consistent
Meaningful
Useful

13. Answer: Consistent