Why is a sample variance for proportions biased?

I am not certain of the context here. Taking the variance of a sample of proportions is biased because we assume that the proportion is the p in a binomial distribution. Calculation of the binomial variance of a single proportion the “regular way” is often considered unbiased. read more

Taking the variance of a sample of proportions is biased because we assume that the proportion is the p in a binomial distribution. Calculation of the binomial variance of a single proportion the “regular way” is often considered unbiased. read more

One way of seeing that this is a biased estimator of the standard deviation of the population is to start from the result that s2 is an unbiased estimator for the variance σ2 of the underlying population if that variance exists and the sample values are drawn independently with replacement. read more