Logit Model

Also known as · logit · logistic regression · discrete-choice

The logit model is a binary-outcome model estimating Pr⁡(y=1∣x)=exp⁡(x′β)/[1+exp⁡(x′β)]\Pr(y = 1 \mid \mathbf{x}) = \exp(\mathbf{x}'\boldsymbol\beta) / [1 + \exp(\mathbf{x}'\boldsymbol\beta)] — the logistic CDF applied to the linear index. Like probit, logit squashes predictions into [0,1][0, 1], fixes the LPM's unbounded-probability problem, and is estimated by MLE. The two models give nearly indistinguishable predictions in practice.

When to use

Same domain as probit — binary outcomes where the LPM's drawbacks bite. Logit has the advantage that coefficients can be interpreted as log-odds (a one-unit increase in xjx_j multiplies the odds p/(1−p)p/(1-p) by exp⁡(β^j)\exp(\hat\beta_j)); the AME is computed via dlogis(). Use whichever your instructor prefers — the choice is rarely substantive. R: glm(y ~ x, family = binomial(link = "logit"), data = df).

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