Minimum sample size calculations:

This application calculates the minimum sample of respondents needed in order to achieve the required level of research accuracy.

By taking into account an expected percentage, as well as the corresponding confidence interval, it is possible to calculate the sample size needed for a given market research survey.

For instance

Research is needed to evaluate the level of use of Product A among anaesthetists. The desired confidence interval is +/-8. Approximately one third of anaesthetists is expected to be using Product A.

How many anaesthetists need to be interviewed in order to achieve this margin of error?

At 5% risk level*, for an expected percentage of 33%, with a confidence interval of +/-8, minimum sample size is 133 anesthetists.

In other words, if you interview a minimum of 133 anesthetists, there is a 95% chance to get a confidence interval of +/-8 if the proportion of Product A users in the anesthetist sample is 33%.