Sigmoid

An S-shaped function that squeezes any number into the range 0 to 1.

Other terms from the same lesson

• coefficient: Another name for a weight in a linear or logistic regression: how much one feature pushes the prediction.
• decision boundary: The line (or surface) where a model switches from answering yes to answering no.
• log-odds: The natural log of the odds. Logistic regression's score is a log-odds: 0 means 50/50, positive leans yes, negative leans no.
• logistic regression: A simple classifier: a weighted sum of inputs squeezed into a probability between 0 and 1.
• odds: The chance something happens divided by the chance it doesn't. A 75% chance is odds of 3 (3 to 1).
• odds ratio: How much the odds get multiplied when one feature goes up by 1. Above 1 raises the odds; below 1 lowers them.
• threshold: A cutoff value: on one side the answer is yes, on the other no. A classifier often says yes above a probability of 0.5.