Namely, if the target variable is . the proportion of drivers making n trips per day, assuming that this proportion is totally unknown a priori (and so in the worst case) a random sample of 600 individuals can provide the estimation of this proportion with a confidence interval of in the 95 of the cases. This means that if the estimated proportion is 20%, the confidence interval will be 16-24%. Since the sample is stratified rather than a pure random one, the interval can be narrower. Instead, if we consider the estimation of an average value (. the.
