Range | Descriptive | Amount of spread between the extremes of the data | Highest data point minus the lowest |

Standard deviation (SD) | Descriptive | Typical or (roughly speaking) average difference between the data points and their mean | |

Standard error (SE) | Inferential | A measure of how variable the mean will be, if you repeat the whole study many times | SE = SD/√n |

Confidence interval (CI), usually 95% CI | Inferential | A range of values you can be 95% confident contains the true mean | *M* ± *t*_{(n–1)} × SE, where *t*_{(n–1)} is a critical value of *t*. If *n* is 10 or more, the 95% CI is approximately *M* ± 2 × SE. |