1. AQA Questions and answers
Experimental design
AQA Questions and answers
This was interesting
Not for watching in the lesson background. How to get somebody to go out with you!

2. Experimental Design Summary
Experimental design refers to how participants are allocated to the different conditions (or IV groups) in an experiment. There are three types:
1. Independent measures / groups: Different participants are used in each condition of the independent variable.
2. Repeated measures: The same participants take part in each condition of the independent variable.
3. Matched pairs: Each condition uses different participants, but they are matched in terms of certain characteristics, e.g. sex, age, intelligence etc.

3. Questions
A psychologist carried out an experiment using an independent groups design. The psychologist wished to investigate the effectiveness of a strategy for memory improvement. In one condition, participants were taught a memory improvement strategy. In the other condition, participants were not taught this memory improvement strategy. All participants were asked to memorise 10 pictures of familiar objects. For example, the first was a doll, the second was an apple. All participants were then given 50 pictures each, and asked to select the original 10. The psychologist did a pilot study before carrying out the experiment. The results of the experiment are shown in the table below.

4. questions 2 (a) Write a directional hypothesis for this experiment. 2
2 (b) Explain what is meant by an independent groups design. 1
2 (c) Explain one strength and one limitation of using an independent groups design. 4
2 (d) Explain why the psychologist did a pilot study. 3
2 (e) What do the standard deviations in Table 1 tell us about the performance of the two groups? 2
2 (f) Outline one strategy for memory improvement which the psychologist could have taught the participants in this experiment. 4

5. Answers 2 (a) Write a directional hypothesis for this experiment. 2
Participants who use a memory improvement strategy will correctly identify more pictures/objects than participants who do not use a memory improvement strategy.
2 (b) Explain what is meant by an independent groups design. 1
Different participants/people in each condition/group.
Different/separate groups
Random allocation to groups/conditions
2 (c) Explain one strength and one limitation of using an independent groups design. 4
Strength
The participants are naïve because they take part in only one condition, so are less likely to show demand characteristics. There are no order effects such as practice or fatigue because participants take part in one condition. Psychology A (PSYA1) - AQA GCE Mark Scheme 2011 June series
Limitation
Individual variation, because there are different participants in each condition. More participants are needed than if a repeated measures design was used
2 (d) Explain why the psychologist did a pilot study. 3
A pilot study is used to check aspects of the research such as whether participants understand standardised instructions, whether timings are adequate etc. It allows the researcher to try out the study with a few participants so that adjustments can be made before the main study, so saving time and money.
2 (e) What do the standard deviations in Table 1 tell us about the performance of the two groups? 2
The standard deviation (spread of scores) is larger in the condition with the memory improvement strategy.

6. Why is this important.
Learn the answers. There are only a few questions they can ask in this topic.

7. Question
A psychologist used an independent groups design to investigate whether or not a cognitive interview was more effective than a standard interview, in recalling information. For this experiment, participants were recruited from an advertisement placed in a local paper. The advertisement informed the participants that they would be watching a film of a violent crime and that they would be interviewed about the content by a male police officer. The psychologist compared the mean number of items recalled in the cognitive interview with the mean number recalled in the standard interview

8. Questions 3 (a) Name the sampling technique used in this experiment. 1
3 (b) Suggest one limitation of using this sampling technique. 2
3 (c) Identify the independent variable and the dependent variable in this experiment. 2
3 (d) Explain one advantage of using an independent groups design for this experiment. 2
3 (e) Discuss whether or not the psychologist showed an awareness of the British Psychological Society (BPS) Code of Ethics when recruiting participants for this experiment. 3

9. Answers 3 (a) Name the sampling technique used in this experiment. 1
Volunteer/volunteering or self-selected/self-selecting sample.
3 (b) Suggest one limitation of using this sampling technique. 2
A limitation of a volunteer sample is that it is biased/not representative (1 mark) because some people are more likely to volunteer than others (1 mark) or the findings cannot be generalised to a population (1 mark).
3 (c) Identify the independent variable and the dependent variable in this experiment. 2
IV The interview, type of interview, method of interview, „standard interview or/and cognitive interview‟, whether or not cognitive interview.
DV Number of items recalled, recall, what they remembered.
3 (d) Explain one advantage of using an independent groups design for this experiment. 2
There is better control because the same film can be used in both conditions. The participants are less likely to show demand characteristics because they take part in only one condition. There are no order effects such as practice or fatigue, because participants take part in one condition. 1 mark for very brief or slightly muddled advantage. 2nd mark for accurate elaboration.
3 (e) Discuss whether or not the psychologist showed an awareness of the British Psychological Society (BPS) Code of Ethics when recruiting participants for this experiment. 3
The question asks about recruiting participants, so answers referring to debriefing are not relevant.
There was no deception. Participants knew they would be watching a film of a violent crime and that they would be interviewed about the content by a male police officer before they volunteered. This gave them the opportunity to give informed consent.
Students may argue that the psychologist did not follow BPS guidelines eg because they were not told of their right to withdraw.

10. Sampling
Random sampling: Everyone in the entire target population has an equal chance of being selected.
Opportunity sampling: Uses people from target population available at the time.
Systematic sampling: Chooses subjects in a systematic way. For example, every 10th person from a list or register.
Self-selected sample: Participants volunteer. For example, by answering an advert.
Stratified sampling: Divides target population into groups, people in sample from each group in same proportions as population. So you would have a higher number of people between the ages of than

11. Learn

12. Question
A Level exam tips Answering exam questions (PSYA1 AQA A specification) Questions about types of experiments tend to be 1 or 2 mark questions that require you to: Identify the type of experiment in an example
Give 1 strength and 1 weakness of that type of experiment
As only one strength or weakness will be required in the answer, it is sensible to learn 2 for each type of experiment (6 in total) and be able to explain them with a brief example.
Questions about experimental designs also tend to be 1 or 2 mark questions that require you to: Identify the experimental design in an example
Give 1 strength and 1 weakness of that experimental design
As only one strength or weakness will be required in the answer, it is sensible to learn 2 for each design (6 in total) and be able to explain them with a brief example.

13. Minimising researcher effects and demand characteristics
There are several things a researcher can do:
Disguise the purpose of the investigation: There is some deception in many psychological studies to stop participants guessing the aims and changing their behaviour. Participants in Milgram's obedience studies thought it was a study on effects of punishment on learning and memory.
Single-blind design: Participants do not know which condition (experimental or control) they are in. For example, the use of placebos in trials of drug treatments.
Double-blind design: Neither the participants nor the experimenter know which condition people are being treated to. For example, a research assistant giving out drugs and measuring their effects does not know who has the placebo and who has the drug.

14. Sampling
Sampling techniques are very important. Several different types of sampling are used according to the type of study and the subjects you want to target.
Random sampling: Everyone in the entire target population has an equal chance of being selected.
Opportunity sampling: Uses people from target population available at the time.
Systematic sampling: Chooses subjects in a systematic way. For example, every 10th person from a list or register.
Self-selected sample: Participants volunteer. For example, by answering an advert.
Stratified sampling: Divides target population into groups, people in sample from each group in same proportions as population. So you would have a higher number of people between the ages of than

15. Types of Hypotheses
A hypothesis (plural hypotheses) is a precise testable statement of what the researchers predicts will be the outcome of the study.

16. null hypothesis 
The null hypothesis states that there is no relationship between the two variables being studied (one variable does not affect the other). It states results are due to chance and are not significant in terms of supporting the idea being investigated.

17. Directional hypotheses
A directional prediction of what is expected to happen. It states which condition of the IV will perform better or worse than the other. It must include the DV and be operationalised.
Male participants will score more basketball hoops than female participants.
Participants who have been trained in a memory improvement strategy will correctly recall more items from a list than participants who have not been trained.

18. Nondirectional hypotheses
A nondirectional prediction of what is expected to happen. It states that there will be a difference between the conditions of the IV, but it does not state which will perform better or worse. It must include the DV and be operationalised.
There will be a difference between male and female participants in the number of basketball hoops scored.
There will be a difference in the number of items correctly recalled from a list between participants who have had memory improvement training and those who have not.