Extend a trend beyond the observed data and quantify the growing uncertainty.
Extrapolation assumes the observed relationship continues unchanged. Uncertainty grows faster than linearly with distance beyond the data, which the widening multiple makes explicit. Extrapolating twice the observed range roughly triples the prediction interval, which is usually the point at which a forecast stops being useful.
Extrapolation
Extrapolation uses the fitted slope; uncertainty grows with distance beyond the observed range
Extrapolation uses the fitted slope; uncertainty grows with distance beyond the observed range Extrapolation assumes the observed relationship continues unchanged. Uncertainty grows faster than linearly with distance beyond the data, which the widening multiple makes explicit.
Extrapolating twice the observed range roughly triples the prediction interval, which is usually the point at which a forecast stops being useful.
This calculator takes 6 inputs: First x value, First y value, Second x value, Second y value, Target x value beyond the data, Residual standard error. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.