Standard deviation describes how much variability—or fluctuation—exists within a data set. The standard error of the mean (SEM) indicates how accurately a data set represents the true population by ...

Error bars illustrate the margin of error for a survey estimate by showing how precise that estimate is. Here are some answers to common questions that might help you better understand charts with ...

For a given data set, standard deviation measures how spread out the numbers are from an average value. This measurement of average variance has a prominent place in many fields related to statistics, ...