A researcher investigating occupational stress at a hospital obtains an alphabetical list of all 800 medical staff members. Beginning at a randomly selected starting point, the researcher selects every 20th20^{\text{th}}20th name on the list to invite to complete a stress questionnaire. Which sampling technique is being used?
Stratified
Opportunity
Systematic
Self-selected
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.