Groups of 100, by contrast, are almost always going to have similar means, because variability is averaged out. Groups of 5 are likely to have a lot of variability in the means, because if one person is very tall or very short, the mean will be thrown off. how much individual variability there is), and the sample size – as you choose larger and larger groups of people, the means will deviate less.

HOW different they were would be a function of both the SD (i.e. Then, imagine you measured the height of another ten random people. Now, imagine you measured the average height of ten random people. With reasonably large sample sizes, SD will always be the same. If you only measured 500 people, your standard deviation would still be very close to 3.0 cm. This tells you how much individual variability there is among individuals. It is different, however, in that while the Standard Deviation gives one a sense of how much variability there is in the individual values that make up one single sample, the Standard Error of the Mean gives one a sense of how much variability there is in the means of small samples (of n individual values) of a larger population.Īs an example, assume that you measured the height of a population of 1000 people. The Standard Error of the Mean (SE(M)) is analogous to the Standard Deviation (SD), in that it is an estimate of variability.

Standard error