interpolation

1. Estimation of an unknown quantity between two known quantities (historical data), or drawing conclusions about missing information from the available information. Interpolation is useful where the data surrounding the missing data is available and its trend, seasonality, and longer-term cycles are known. Time series analysis and regression analysis are the two statistical techniques employing the concept of interpolation. See also extrapolation.

2. Insertion of words into a document purportedly to clarify its contents but often to change their meaning.