The general understanding is:

  • Predict: past value - could be data the model has seen (data from train set) or past data model has not seen (data from test set) (together in-sample data)
  • Forecast: future value - data which neither model or user has seen (out-of-sample data)

Related question: https://stats.stackexchange.com/questions/65287/difference-between-forecast-and-prediction

Question: Is there a common word that can mean either? This will help in talking or writing or explaining to non-technical people.

  • $\begingroup$ You might want to post also here (english.stackexchange.com) $\endgroup$ Commented Jun 23, 2020 at 7:05
  • 2
    $\begingroup$ I disagree with your definition of "predict", the word is not specific to past value. As the top answer in the linked question says "Forecasting would be a subset of prediction", so the word predict can be used to mean forecast as well. $\endgroup$
    – Erwan
    Commented Jun 23, 2020 at 11:51
  • $\begingroup$ Agree with @Erwan: "to predict" is something very general. Forcasts - to my understanding - refer to future periods in time. This is not necessarily the case with predictions. So I guess both words have a different notion after all. $\endgroup$
    – Peter
    Commented Jun 23, 2020 at 12:20

1 Answer 1


I am not sure if I agree with the first one, since predict is widely used to replace forecast as well. But other related verbs we often hear are:

  • To estimate
  • To infer / make an inference

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