Modelling & prediction

Predicting values where nobody measured them, and deciding where things should go — with the limits of each model attached.

Scattered samples, the surface fitted through them, and the uncertainty that grows away from the data. a prediction without its support is a picturesamplesa surfaceand its limitsEvery topic here is about the third panel: where the model is allowed to speak, and how loudly

Three topics that answer questions the data does not contain: what is the value where nobody measured, and where should the next thing go?

Both are answerable, and both are easy to overstate. An interpolated surface honours every sample and is a guess everywhere else — and which guess depends on the method, so the same five measurements produce different surfaces under IDW, kriging and a spline. A machine-learning model scores well on a random split because neighbouring rows are nearly the same row, and it will predict cheerfully over ground it has never seen. A location model optimises exactly the objective you wrote down, which is rarely exactly the objective you meant.

What ties them together is the third thing every prediction needs: not just a value, but the area and the conditions it is allowed to speak for.

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