Data Handling: Descriptive Statistics & Computation (AQA A Level Psychology)

A psychologist wanted to test whether listening to music improves running performance.

The psychologist conducted a study using 10 volunteers from a local gym. The psychologist used a repeated measures design. Half of the participants were assigned to condition A (without music) and half to condition B (with music).

All participants were asked to run 400 metres as fast as they could on a treadmill in the psychology department. All participants were given standardised instructions. All participants wore headphones in both conditions. The psychologist recorded their running times in seconds. The participants returned to the psychology department the following week and repeated the test in the other condition.

The results of the study are given in Table 1 below

Table 1 Mean number of seconds taken to complete the 400m run and the standard deviation for both conditions

What do the mean and standard deviation values in Table 1 suggest about the participants’ performances with and without music? Justify your answer.

Calculate the percentage decrease in the mean time it took participants to run 400 metres when listening to music. Show your workings. Give your answer to three significant figures.

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 collated the responses of all the participants over the two-week period and calculated the mean and standard deviation for each condition.

Table 1 Mean number of nightmares reported and the standard deviation for each condition

What do the mean and standard deviation values in Table 1 suggest about the effect of the type of film watched on the occurrence of nightmares? Justify your answer.

A psychologist decided to design an experiment to test the effects of recreational screen time on children’s academic performance.

The psychologist randomly selected four schools from all the primary schools in her county to take part in the experiment involving Year 5 pupils. Three of the four schools agreed to take part. In total, there were 58 pupils whose parents consented for them to participate. The 58 pupils were then randomly allocated to Group A or Group B.

For the two-week period of the experiment, pupils in Group A had no recreational screen time. Pupils in Group B were allowed unrestricted recreational screen time. At the end of the experiment all pupils completed a 45-minute class test, to achieve a test score.

The results obtained from the experiment are summarised in Table 1.

Table 1 Descriptive statistics for the test performance scores for Group A and Group B

What do the mean and standard deviation values in Table 1 suggest about the effect of recreational screen time on test performance? Justify your answer.

There was an overall increase in sales of Tiger following the advertisement campaign. Interestingly, the increase in sales was greater for male customers than for female customers. See Table 1 below.

Table 1 Sales figures before and after the Tiger advert

Calculate the percentage increase in sales of Tiger to male customers. Give your answer to two significant figures.

Show your workings.

Julia complains that her baby is sleeping all day and keeping her awake all night.

Julia decided to record how many hours her baby slept for in the day and in the night for box one week.

Table 1 The number of hours slept in the day and the number of hours slept in the night over one week

Calculate the mean number of hours slept in the night. Show your workings.

Give your answer to two significant figures.

A researcher investigated retrieval failure using an independent groups design.

In Condition A, 10 participants learnt 30 words and recalled them in the same room.

In Condition B, another 10 participants learnt the same 30 words in one room and recalled them in a different room.

The results for Condition B are shown below.

Table 1

The researcher decided to use the mean to analyse the results

Suggest a more appropriate measure of central tendency for this data set and explain why it would be more appropriate.

In 1987, a survey of 1000 young people found that 540 said they smoked cigarettes, whilst 460 said they did not. In 2017, a similar survey of another 1000 young people found that 125 said they smoked cigarettes, whilst 875 said they did not.

Calculate the ratio of smokers to non-smokers in 2017. Give your answer in its simplest form.

Show your workings.

Researchers studied therapies for schizophrenia. They assessed the mood of two groups of participants before the participants received therapy. The same participants were assessed again after four weeks of receiving therapy.

Group 1 (Drug therapy group) received drug therapy alone.

Group 2 (Combined therapy group) received a combination of drug therapy and cognitive therapy.

The researchers assessed mood using a standardised test of mood. A low score indicated negative mood and a high score indicated positive mood. Scores ranged from 0 to 100. The lowest score was 24 and the highest score was 83.

Table 1 shows the results of the study after four weeks of therapy.

Table 1 Mean mood scores for Group 1 (Drug therapy group) and Group 2 (Combined therapy group) after four weeks of therapy

Explain why the data in Table 1 does not enable the researchers to draw proper conclusions about the effectiveness of therapy for the two groups. What should the researchers do about this?