Up Learn – A Level PsychologY (AQA)

Research Methods (Part 1)

Last time, we looked at the effects of extraneous variables on validity and reliability, and saw that extraneous variables reduce both the validity and the reliability of a study.

So, because of all of the uncontrolled extraneous variables in her study, – like room temperature, and puppy personality, – Patty’s study lacks validity and reliability.

But Patty doesn’t want her study to lack validity and reliability, so, what can she do about it? How can she control her extraneous variables?

One way to control extraneous variables is through standardisation.

In Patty’s study, if everyone sits in different types of chair [show range of chairs varying from super comfy to shit stools], so some participants sit on horrible hard stools and others on nice comfy sofas [add people to chairs], some of her participants will end up feeling in a better mood than others [people on stools look grumpy, those on sofa look happy].

And that could influence the responses participants give on the depression questionnaire.

But if instead, Patty makes sure all of her participants are sitting on chairs that are exactly the same, then, she’ll know that any changes she sees in her participant’s mood and depression score WON’T be due to the chairs…

And the chairs will no longer influence the results of the study.

When researchers make an extraneous variable the same for all of the participants in a study, we say that they have standardised the extraneous variable.

If Patty’s participants are all sitting on different types of chairs, then Patty has not standardised the chairs.

But if Patty makes all the chairs the same in her study, then she has standardised the chairs.

Even if Patty makes all her participants sit on hard stools, then, she will have standardised the chairs – because the type of chair will be the same for everyone.

So, which of the following extraneous variables have been standardised?

These have been standardised, but these haven’t!

To sum it up, one way to control extraneous variables is through standardisation, which is when researchers make an extraneous variable the same for all participants in a study.