Understanding Psychology at A level and GCSE: 8
Here is the 8th in our new series of Psychology blogs – useful for anyone revising for exams or thinking about taking up Psychology as a new subject at A level or GCSE.
Independent and Dependent Variables in Psychological Research
Many psychology students get confused about independent and dependent variables.
Every psychological experiment has an independent variable and a dependent variable.
You may get asked in an exam to identify the independent and dependent variable in an experiment, so it is important to be clear on the difference between the two.
The Independent Variable (IV) is what you are manipulating. It is the thing that causes a change in the outcome/result.
The Dependent Variable (DV) is what you are measuring.
For example, if I was measuring the effect of watching violent TV programmes on aggression levels, my IV would be violent TV programmes as this is what I am manipulating – watching violent or non-violent TV programmes. My DV would be aggression, as this is what I am measuring.
If I decide to conduct an experiment to see whether students who study in the afternoon will perform better in exams than students who study in the morning, what would my hypothesis be?
Well, I might have a hypothesis such as:–
‘There will be no difference in exam performance between students who study in the morning and those who study in the afternoon.’ (My null hypothesis)
Or I might have a directional hypothesis:–
Students who study in the afternoon will perform better in exams than students who study in the morning.
What would my IV and DV be?
Well, I am looking at exam performance, so this is what I am measuring. So my DV would be exam performance.
My IV is what I am manipulating in my experiment. So I am manipulating when students study. I will ask some students to study in the morning and some to study in the afternoon. So my IV would be when they study – morning or afternoon.
See my next blog for some sample questions on IVs and DVs.
Tracey Jones
Psychology Tutor
