Reliability & Validity (AQA A Level Psychology)

A psychologist decided to conduct an experiment to investigate the effect of watching horror films before going to bed.

A volunteer sample of 50 university students consented to take part in the experiment.

The 50 students were randomly split into two groups. Group 1 watched a horror film before going to bed each night for the first week then a romantic comedy before going to bed each night for the second week. Group 2 watched the romantic comedy in the first week and the horror film in the second week.

When the students woke up each morning, each student received a text message that asked if they had had a nightmare during the night. They could respond ‘yes’ or ‘no’.

The psychologist was concerned about the validity of the experiment.

Suggest one possible modification to the design of the experiment and explain how this might improve validity.

A controlled observation was designed to compare the social behaviours of pre-school children of working parents and pre-school children of stay-at-home parents.

The sample consisted of 100 children aged three, who were observed separately. Half of the children had working parents and the other half had stay-at-home parents. The observation took place in a room which looked like a nursery, with a variety of toys available. In the room, there were four children and one supervising adult. Their behaviour was not recorded.

Each child participant was brought into the room and settled by their parent. The parent then left to sit outside. Each child participant’s behaviour was observed covertly for five minutes while they played in the room.

The observation was conducted in a controlled environment and a standardised script was used when the children and their parents arrived.

Explain how the reliability of the controlled observation could be assessed through inter-observer reliability.

A researcher wanted to investigate whether there was a relationship between locus of control and resistance to social influence. Before the investigation began, he devised a questionnaire to measure locus of control.

To assess the questionnaire’s validity, the researcher gave it to 30 participants and recorded the results. He then gave the same 30 participants an established questionnaire measuring locus of control. The researcher found a weak positive correlation between the two sets of results, suggesting that his questionnaire had low validity.

Explain how the validity of the researcher’s questionnaire could be improved.

A controlled observation was designed to compare the social behaviours of pre-school children of working parents and pre-school children of stay-at-home parents. The sample consisted of 100 children aged three, who were observed separately. Half of the children had working parents and the other half had stay-at-home parents.

The observation took place in a room which looked like a nursery, with a variety of toys available. In the room, there were four children and one supervising adult. Their behaviour was not recorded.

Each child participant was brought into the room and settled by their parent. The parent then left to sit outside. Each child participant’s behaviour was observed covertly for five minutes while they played in the room.

The observation was conducted in a controlled environment and a standardised script was used when the children and their parents arrived.

Explain one reason why collecting quantitative data could reduce the validity of this study.

A psychologist was interested in finding out whether dream themes differed between males and females, particularly in terms of social interaction. She decided to conduct a pilot study. Twenty undergraduate students (8 male and 12 female) volunteered for the study. For a six-week period the students were interviewed at 9 am each morning when they arrived at university. Interviewers, who did not know the purpose of the study, carried out and recorded the dream interviews.

Another researcher, who did not know the purpose of the study, carried out a content analysis of the interview data.

The psychologist wanted to assess the reliability of the content analysis.

Explain how the reliability of the content analysis could be assessed.

It was recently reported in a newspaper that time spent playing team sports increases happiness levels. A researcher was keen to find out whether this was due to participating in a team activity or due to participating in physical activity, as he could not find any published research on this.

The researcher used a matched-pairs design. He went into the student café and selected the first 20 students he met. Each student was assigned to one of two groups.

Participants in Group A were requested to carry out 3 hours of team sports per week. Participants in Group B were requested to carry out 3 hours of exercise independently in a gym each week. All participants were told not to take part in any other type of exercise for the 4-week duration of the study.

All participants completed a happiness questionnaire at the start and end of the study. The researcher then calculated the improvement in happiness score for each participant. The questionnaire had high concurrent validity.

The questionnaire had high concurrent validity.

Validity was still a concern because the researcher knew which participants were in each experimental group.

Explain how this could have affected the validity of the study.