7.5 a If you assume that there are at least 100,000 managing directors of small to mediumsized organisations from which to select your sample, you will need to interview approximately 380 to make generalisations that are accurate to within plus or minus 5 per cent ( Table 7.1 ). b Either cluster or multi-stage sampling could be suitable; what is important is the reasoning behind your choice. This choice between cluster and multi-stage sampling is dependent on the amount of limited resources and time you have available. Using multi-stage sampling will take longer than cluster sampling as more sampling stages will need to be undertaken. However, the results are more likely to be representative of the total population owing to the possibility of stratifying the samples from the sub-areas.