# From score to probability. Meet the sigmoid.

Turn an unbounded score into a model probability and connect the surface to the 2D boundary.

Part 3 of the six-part logistic regression series. Predict, explore and explain one idea through numerical controls, a focused interactive, hints and thinking questions.

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Canonical page: https://21ifm.com/ml/sigmoid

## Explore

- [View the whole logistic regression series](https://21ifm.com/ml)
- [Try a free foundation lesson with Zon](https://21ifm.com/basics/sine)