Experimental Design Flashcards
What is independent groups
The clues in the name this design is separate groups of people for each level of the IV in the experiment. Like one group would be used to for one part and the other for the other
Strengths for Independent groups
Order effects are not a problem- each P only does the task once therefore no practise effect
Weaknesses of Independent Groups
The Ps in each groups may differ. Participant variables therefore the difference in results be more to do with participant variables then the change in IV. Reducing the validity of the results
What is the repeated measure design
All the Ps receive all levels of the IV (involved in all conditions of the experiment) so they repeat the task
Strength of Repeated Measures
No problem with participant variables. As each P is compared against themselves rather than others.
Another strength is that fewer Ps are needed than in independent groups.t his means the study may be less expensive
Weaknesses of repeated Measures
Order effects. When the Ps are tested twice the order in which they do the task may make a difference. Performances might be better a second time because of practice rather than the IV reducing the validity of the results
How do you deal with order effects in repeated measures
Counter balancing , first half of the Ps complete the conditions in order and the other one in the opposite order.
What is Matched Pairs
Ps take part in one condition of the experiment but they are like matched up with other ps tested on key participant variables. Each pair is allocated to a different group of the experiment
Strengths of matched pairs
It’s able to deal with the problems between the other 2 experiments, Ps only tested once so no order effects
The Ps are matched so fewer participant variables
Weaknesses of Matched Pairs
Matching takes time and its never exact.
Plus it’s likely that only one or two key variables will be matched so others will remain.
Method sometimes involves quite a lot of effort for little gain
What is random sampling
Putting names of all members of the target population into a hat/computer programme so that every member of the target population has an equal chance of being selected.
Evaluate random sampling
Evaluation
A strength is that there is no bias. Every person in the target population has an equal chance of being selected. This makes the sample more representative.
A weakness is that it takes more time and effort than other methods. This is because you need to obtain a list of all the members of your target population and then randomly select them. The effort may not be worth it.
What is opportunity sampling
Selecting the most readily available group of people.
What is systematic sampling
Selecting every nth person from a list of all the people in the target population.
Evaluate Systematic Sampling
Evaluation
A strength is that it avoids researcher bias. The researcher has no say over who is selected. This makes it more representative.
A weakness is that it may still be biased. You might end up with a sample consisting of one particular group of people. This decreases the representativeness.
