Why is reliability important?
Hello! So, the blogs have changed slightly. This is going to be my blog for weeks 4 and 5. I’m going to be discussing why reliability is important when we’re doing research.
So first, what is reliability? And how can we measure it?
I’m pretty sure that if you’re reading this blog then you know all about reliability in a study, but I shall briefly explain anyway.
Firstly, reliability is very closely linked with validity, but it’s important not to get the 2 mixed up. Validity is whether your test measures what you want it to measure. Reliability is a little different.
What is it?
Reliability is simply the consistency of a measure. We could consider our result reliable if we get the same one repeatedly. So, if we conducted an experiment to see if mood is affected by weather and found that it was, would we also find that same result when the test was conducted again? (this is an example of test-rest reliability…which I’ll come to in a second).
If so, the results could be considered reliable.
How can we measure it?
There are actually many ways to test reliability:
- Test-retest reliability – which is when a test is administered at 2 different points in time to assess the consistency of a test across time.
- Inter-rater reliability – this uses 2 or more experimenters to score the test. The scores are then compared to compare the consistency of the rater’s estimates.
- Parallel-forms reliability – this uses 2 different tests, which were created using the same content.
- Internal consistency reliability – this is when 2 questions (most often on a questionnaire) ask the same thing. If the 2 answers match, that shows reliability.
I have gone into these in very brief detail, and there is more detail if anybody wants it here:
Now, is reliability important in Psychological testing? Well, of course it is. If an experimenter got different results every time they did the test, then how would they know which results were the true ones? They couldn’t answer their research question. If they found from one test that weather does affect mood, and on another they found that weather has no effect on mood – does weather affect mood? There’s no way to know because those results aren’t reliable.
Now, if that were the case then that’s when they might look at the validity of the study and see if it was something other than the weather affecting people’s mood – were they actually measuring what they set out to measure? (Which is where reliability and validity are so closely linked, and where it might be easy to get the 2 confused).
So, I shall end by saying that if results aren’t reliable, there’s probably no point in putting any store in these results at all.
I’m going to be having a couple of weeks off from writing my blogs (please, don’t cry), so see you all after exam week, and if you’re a 2nd year Psychology student at Bangor (which I’m sure you are) good luck in your exams!!