Standard Error

As opposed to a really special one.

When we create a sampling distribution to estimate a population mean, proportion, standard deviation, or some other value, we’re dealing with a whole bunch of same-sized samples taken from the same population. Each one of these samples gave us a mean, for example. If we find the standard deviation of each of these means from each of these samples, we have calculated the standard error which is a measure of how variable the means from all of our samples are compared to the actual mean of the population. A quick comparison for clarity.

A standard deviation measures the variability (or spread) in the individual data points in one sample. A standard error measures the variability (or spread) in the value (like a mean, proportion, standard deviation, etc.) we calculate from repeated samples.