A line chart in which a sharp increase or decrease occurs over a period of time. The line connecting the data points resembles a hockey stick, with the "blade" formed from data points shifting diagonally and the "shaft" formed from the horizontal data points. Hockey stick charts have been used as a visual to show dramatic shifts, such as global temperatures and poverty.

A sudden and dramatic shift in the direction of data points from a flat period to what is visible in a hockey stick chart is a clear indicator that more attention should be paid in order to determine the cause. If the data shift occurs over a short time period, it is important to determine if the shift is an aberration or if it represents a fundamental change.