A psychologist wanted to investigate whether reducing evening screen-time would affect sleep quality in 17-year-olds. Previous research into the effects of blue light on sleep in teenagers had shown that limiting mobile device usage before bed improved sleep quality.
The psychologist decided to use a repeated measures design to investigate the effects of evening screen use on sleep quality in 25 17-year-old students. All the students were preparing for their end-of-term exams.
For Condition A, students were required to turn off their mobile phones and and avoid all electronic screens for at least 60 minutes before going to sleep each night for one week.
In Condition B, students continued their usual screen-time habits in bed before going to sleep each night for one week.
At the end of each week of the investigation, for both Condition A and Condition B, each student was asked to rate their overall sleep quality on a rating scale of 1–10, where a higher self-reported rating indicated better sleep quality.
Explain one strength and one limitation of collecting quantitative data in this study.
235 exam-style questions on AQA A Level Psychology Data handling and analysis. Each one has a worked solution and a mark scheme showing where the marks go.