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We assume that the probabilities of these outcomes are given by p 1 (x), p 2 (x), p 3 (x), p 4 (x), p 5 (x), all of which are functions of some independent variable(s) x. Then, for a fixed value of x, the logarithms of the odds (not the logarithms of the probabilities) of answering in certain ways are:
Multinomial logistic regression is known by a variety of other names, including polytomous LR, [2] [3] multiclass LR, softmax regression, multinomial logit (mlogit), the maximum entropy (MaxEnt) classifier, and the conditional maximum entropy model.
[1] [2] Examples of ordinal regression are ordered logit and ordered probit. Ordinal regression turns up often in the social sciences, for example in the modeling of human levels of preference (on a scale from, say, 1–5 for "very poor" through "excellent"), as well as in information retrieval.
A graph of the logistic function on the t-interval (−6,6) is shown in Figure 1. Let us assume that t {\displaystyle t} is a linear function of a single explanatory variable x {\displaystyle x} (the case where t {\displaystyle t} is a linear combination of multiple explanatory variables is treated similarly).
In statistics and econometrics, the multinomial probit model is a generalization of the probit model used when there are several possible categories that the dependent variable can fall into. As such, it is an alternative to the multinomial logit model as one method of multiclass classification .
Discrete choice models take many forms, including: Binary Logit, Binary Probit, Multinomial Logit, Conditional Logit, Multinomial Probit, Nested Logit, Generalized Extreme Value Models, Mixed Logit, and Exploded Logit. All of these models have the features described below in common.
The softmax function, also known as softargmax [1]: 184 or normalized exponential function, [2]: 198 converts a vector of K real numbers into a probability distribution of K possible outcomes. It is a generalization of the logistic function to multiple dimensions, and is used in multinomial logistic regression.
where () is the binary entropy function [1] = () () In probability theory and statistics , the logistic distribution is a continuous probability distribution . Its cumulative distribution function is the logistic function , which appears in logistic regression and feedforward neural networks .