Experimental Design

Question 1

What is independent groups

Answer 1

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

Question 2

Strengths for Independent groups

Answer 2

Order effects are not a problem- each P only does the task once therefore no practise effect

Question 3

Weaknesses of Independent Groups

Answer 3

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

Question 4

What is the repeated measure design

Answer 4

All the Ps receive all levels of the IV (involved in all conditions of the experiment) so they repeat the task

Question 5

Strength of Repeated Measures

Answer 5

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

Question 6

Weaknesses of repeated Measures

Answer 6

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

Question 7

How do you deal with order effects in repeated measures

Answer 7

Counter balancing , first half of the Ps complete the conditions in order and the other one in the opposite order.

Question 8

What is Matched Pairs

Answer 8

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

Question 9

Strengths of matched pairs

Answer 9

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

Question 10

Weaknesses of Matched Pairs

Answer 10

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

Question 11

What is random sampling

Answer 11

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.

Question 12

Evaluate random sampling

Answer 12

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.

Question 13

What is opportunity sampling

Answer 13

Selecting the most readily available group of people.

Question 14

What is systematic sampling

Answer 14

Selecting every nth person from a list of all the people in the target population.

Question 15

Evaluate Systematic Sampling

Answer 15

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.

Question 16

What is stratified sampling

Answer 16

Selecting participants in proportion to their frequency in the target population.

Question 17

Evaluate stratified sampling

Answer 17

Evaluation
A strength is that it is the most representative of all the sampling methods. The researcher ensures that all subgroups are represented in proportion to the numbers in the target population. This enhances representativeness.
A weakness is that it is very time-consuming. It may take a while to recruit participants and sort them into subgroups. This discourages researchers from using this method.

Question 18

Evaluate opportunity sampling

Answer 18

Evaluation
A strength is that it is easy, quick and cheap to carry out because you simply choose people who are nearby. This makes the method less expensive.
A weakness is that the sample is likely to be unrepresentative of the population. This is because the sample is drawn from one place. This reduces the generalisability of the results.