You need to undertake a face-to-face interview survey of managing directors of small to medium-sized organisations. From the data you collect you need to be able to generalise about the attitude of such managing directors to recent changes in government policy towards these firms. Your generalisations need to be accurate to within plus or minus 5 per cent. Unfortunately, you have limited resources to pay for interviewers, travelling and other associated costs.

a How many managing directors will you need to interview?

b You have been given the choice between cluster and multi-stage sampling. Which technique would you choose for this research? You should give reasons for your choice.