- A researcher is hired by a cleaning company to survey the opinions of employees on a proposed pension scheme. The company employs 55 managers and 495 cleaners.
To collect data the researcher decides to give a questionnaire to the first 50 cleaners to leave at the end of the day.
- Give 2 reasons why this method is likely to produce biased results.
- Explain briefly how the researcher could select a sample of 50 employees using
- a systematic sample,
- a stratified sample.
Using the random number tables in the formulae book, and starting with the top left hand corner (8) and working across, 50 random numbers between 1 and 550 inclusive were selected. The first two suitable numbers are 384 and 100 .
- Find the next two suitable numbers.