experiment design Flashcards
what is the experimental design
the experimental design refers to the way which participants are used in the experiment
there are three types of experimental designs:
- independent groups
- repeated measures
- matched pairs
what is an independent group
independent groups is an experimental design where two separate groups of participants experience two conditions of the experiment
e.g. if there are two levels of the independent variable (IV) this means that all participants experiences one level of the IV only
these two levels could be the control condition and the experimental condition
The performance of the two groups would be compared
what are repeated measures
all participants experience both conditions of the experiment
the set of the data from both conditions would be compared to see if there was a difference
The repeated measures design at least guarantees that we are comparing “like with like”. This contrasts with independent groups design and asses the performance of two different groups of people, which might be a problem
what is a disadvantage of using repeated measures and how can we overcome this
a major issue with repeated measures is the fact that when participants are tested more than once, and experience all conditions of the experiment, there is an increased likelihood they will become wise to the aims of the experiment
to combat this we use matched pairs
what are matched pairs
in matched pairs, participants are paired together on a variable or variables relevant to the experiment
e. g. in a memory study, participants might be matched on their IQ, as this might be a good indicator of their ability to recall information
- participants with the first and second highest IQ’s are matched together and so on
one of the participants form each pair will be allocated a condition of the experiment. This is an attempt to control for the confounding variable of participant variables and often necessitates the use of a pre - test if matching is to be effective
