For a value that is sampled with an unbiased normally distributed error, the above depicts the proportion of samples that would fall between 0, 1, 2, and 3 standard deviations above and below the actual value.

The standard error, sometimes abbreviated as \displaystyle{ SE }, is the standard deviation of the sampling distribution of a statistic. The term may also be used for an estimate (good guess) of that standard deviation taken from a sample of the whole group.