I think this word means: To examine trends in observed and recorded data, as opposed to “extrapolate”, which means to predict future trends based on current and past data.

Actual definition: \in-TUR-puh-layt, transitive verb:

1. To alter or corrupt (as a book or text) by the insertion of new or foreign matter.
2. To insert (material) into a text or conversation.
3. To insert between other elements or parts.
4. [Mathematics] to estimate a value of (a function) between two known values.

PP: Definition #4?  Lame!