# Sampling Variability: Definition

Sampling > Sampling Variability

## What is sampling variability?

Sampling variability is how much an estimate varies between samples. “Variability” is another name for range; Variability between samples indicates the range of values differs between samples.

Sampling variability is often written in terms of a statistic. The variance 2) and standard deviation (σ) are common measures of variability. You might also see reference to the variability of the sample mean (μ), which is just another way of saying the sample mean differs from sample to sample. Sampling variability only refers to a statistic (i.e. a number generated from a sample)—never a population.

## Variability and Sampling Error

A closely related term (almost a synonym) is sampling error. An error in sampling isn’t a mistake — it’s a measure of how much a value differs from the “true” value. Let’s say the true weight of a population is 150 lbs. You take a sample and find the mean weight for the sample is 151 lbs. The 1 lb difference is an “error.” If you sample again, you might get different mean weights of 148 lbs, or 150.5 lbs, or 153 lbs. The different errors — 1/2 lb, 1 lb, 2 lbs, 3 lbs — are a reflection of the variability between your samples, or sampling variability.