Trend, interpolation and extrapolation
Read the pattern and trend of a time series, estimate a value between recorded ones (interpolation) and beyond them (extrapolation).
📖 Start here: read the steps of the “Lesson” in order (1, 2, 3 …) and answer each question. Then continue with “Practice”.
- Iran: grade 11
Guide
In a time series we look for two things: the trend (overall it rises, falls or stays level) and the pattern (ups and downs that repeat regularly, like warm and cold seasons). A repeating pattern helps us predict the future.
Interpolation means estimating a value between recorded data. If we assume a steady change between two points, we read the value on the line segment joining them.
Extrapolation means estimating a value beyond the recorded data by continuing the same trend. The further we go from the data, the less reliable it is, because we do not know that the trend will go on.