This page estimates the mean, variance, and standard deviation of a sample on the basis of the sample’s reported median and range according to the method devised by S.P. Hozo, B. Djulbegovic, and I. Hozo. In their 2005 paper on the method, the authors concluded by observing:

To proceed according to this method, enter the values for sample size, median, and low and high ends of the range into the designated spaces below and then click the «Calculate» button. Small-sample estimates based on the formulas shown above will be calculated for all samples, irrespective of size. For larger samples, the alternative estimates recommended by Hozo, et al. will also appear.