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To obtain the logistic regression equation expressed in probabilistic terms, we need to include the probabilities in the logistic regression equation:

Recalling that the e function is the opposite of the natural logarithm (ln), we can write:

This function is called a logit function. The logit function, on the other hand, allows us to associate the probabilities (therefore, a value included between 0 and 1) to the whole range of real numbers. It is a link function and represents the inverse of the logistic function.