Talk:Discriminative model

"Discriminative models differ from generative models in that they do not allow one to generate samples..."

Samples of what?

Mcswell 15:13, 12 November 2007 (UTC)

Questions

Here are some questions that should be clarified in this article:

• Why is an SVM a discriminative model? It does not model a probability distribution. If modeling probability distributions is not a necessary condition, it should be removed from the definition.
• Is it true that all supervised learning algorithms are considered to be discriminative because they make predictions in one one direction? (ie X predicts Y, but Y does not necessarily predict X). If so, then why are Decision_trees, Naive_bayes, KNN , etc not on the list next to SVMs?
• Does this diagram represent the kind of data for which discriminative models are well-suited?
• If you train two discriminative models, one to predict X->Y, and one to predict Y->X, do they together form a generative model, since you can use them to predict in both directions? To be considered generative, would the Y->X model need to probabilistically sometimes predict '3' and sometimes predict '4'? Or would it need to return a distribution that specifies the probabilities of '3' and '4'?

Simple question:

"Discriminative models differ from generative models in that they do not allow one to generate samples from the joint distribution of x and y."

they refers to discriminative or generative models? —Preceding unsigned comment added by 146.48.87.25 (talk) 10:14, 26 May 2010 (UTC)

Discriminative vs. Discriminant

Bishop (2007) distinguishes between discriminative approaches that learn p(y|x) use it to construct a decision rule and discriminant approaches that directly learn a discriminant function $\hat{y}=f(x)$ without learning the posterior density. According to this terminology some of the examples listed in this article are not discriminative methods, e.g. SVM. My suggestion would be to introduce the distinction between discriminative and discriminant and create two separate lists. Falk (talk) 21:52, 21 September 2010 (UTC)

Linear discriminant analysis

According to Linear classifier#Generative models vs. discriminative models, LDA is not a discriminative model despite its name. It models each class by a Gaussian, and the constraints on the covariance matrix determine the shape of the decision boundary (linear, quadratic, ..). Amro (talk) 23:43, 29 September 2010 (UTC)