An educational psychologist wants to investigate academic anxiety in a secondary school with N=800N = 800N=800 students. The school has 400 students in Key Stage 3, 240 in Key Stage 4, and 160 in Key Stage 5. The researcher decides to use stratified sampling to obtain a sample of n=50n = 50n=50 students that proportionally represents these three key stages.
Which of the following correctly identifies the number of Key Stage 5 students required for this sample, and describes the correct procedure to ensure a representative, bias-free selection within this stratum?
151515 students, selected by assigning a unique number to each of the 160160160 Key Stage 5 students and using a random number generator to select 151515 numbers.
101010 students, selected by choosing the first 101010 Key Stage 5 students who volunteer after an assembly.
101010 students, selected by assigning a unique number to each of the 160160160 Key Stage 5 students and using a random number generator to select 101010 numbers.
151515 students, selected by taking every tenth student from an alphabetical register of Key Stage 5 students until 151515 are chosen.
644 exam-style questions on OCR A Level Psychology Research methods and techniques. Each one has a worked solution and a mark scheme showing where the marks go.