{"action":"created","issue":{"url":"https://api.github.com/repos/paul-buerkner/brms/issues/80","repository_url":"https://api.github.com/repos/paul-buerkner/brms","labels_url":"https://api.github.com/repos/paul-buerkner/brms/issues/80/labels{/name}","comments_url":"https://api.github.com/repos/paul-buerkner/brms/issues/80/comments","events_url":"https://api.github.com/repos/paul-buerkner/brms/issues/80/events","html_url":"https://github.com/paul-buerkner/brms/issues/80","id":160895520,"number":80,"title":"Strange result with Categorical?","user":{"login":"wfolta","id":5685924,"avatar_url":"https://avatars.githubusercontent.com/u/5685924?v=3","gravatar_id":"","url":"https://api.github.com/users/wfolta","html_url":"https://github.com/wfolta","followers_url":"https://api.github.com/users/wfolta/followers","following_url":"https://api.github.com/users/wfolta/following{/other_user}","gists_url":"https://api.github.com/users/wfolta/gists{/gist_id}","starred_url":"https://api.github.com/users/wfolta/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/wfolta/subscriptions","organizations_url":"https://api.github.com/users/wfolta/orgs","repos_url":"https://api.github.com/users/wfolta/repos","events_url":"https://api.github.com/users/wfolta/events{/privacy}","received_events_url":"https://api.github.com/users/wfolta/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2016-06-17T14:04:00Z","updated_at":"2016-06-17T14:14:22Z","closed_at":null,"body":"I was dusting off a simple illustration of categorical regression on `brms`, and am getting an odd result:\r\n\r\n```\r\nlibrary (brms)\r\nir <- data.frame (scale (iris[, -5]), Species=iris[, 5])\r\n\r\nsystem.time (b2 <- brm (Species ~ Petal.Length + Petal.Width + Sepal.Length + Sepal.Width, data=ir,\r\n                       family=\"categorical\", chains=3, iter=3000, warmup=600,\r\n                       prior=c(set_prior (\"normal (0, 8)\"))))\r\n```\r\n\r\nThis actually runs a bit faster than it did back in the day. But when I predict (in sample), the last 100 points (the last two categories) all split the vote 50/50 between the last two categories, which I believe means it can't differentiate the last two categories.\r\n\r\nI have to admit that I'm not sure if I looked at the prediction back then. (The code was a part of a larger presentation and I only plotted the trace, not the prediction.) Maybe the predictions were the same as now. But maybe there's been a change that I didn't track and now my `brm` call is wrong -- I remember a change in non-linear regression -- or maybe it's an issue?"},"comment":{"url":"https://api.github.com/repos/paul-buerkner/brms/issues/comments/226780002","html_url":"https://github.com/paul-buerkner/brms/issues/80#issuecomment-226780002","issue_url":"https://api.github.com/repos/paul-buerkner/brms/issues/80","id":226780002,"user":{"login":"paul-buerkner","id":12938496,"avatar_url":"https://avatars.githubusercontent.com/u/12938496?v=3","gravatar_id":"","url":"https://api.github.com/users/paul-buerkner","html_url":"https://github.com/paul-buerkner","followers_url":"https://api.github.com/users/paul-buerkner/followers","following_url":"https://api.github.com/users/paul-buerkner/following{/other_user}","gists_url":"https://api.github.com/users/paul-buerkner/gists{/gist_id}","starred_url":"https://api.github.com/users/paul-buerkner/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/paul-buerkner/subscriptions","organizations_url":"https://api.github.com/users/paul-buerkner/orgs","repos_url":"https://api.github.com/users/paul-buerkner/repos","events_url":"https://api.github.com/users/paul-buerkner/events{/privacy}","received_events_url":"https://api.github.com/users/paul-buerkner/received_events","type":"User","site_admin":false},"created_at":"2016-06-17T14:14:22Z","updated_at":"2016-06-17T14:14:22Z","body":"In brms 0.9.0, I changed the implementation of categorical models to be more flexible (but a bit slower with respect to sampling speed). See my latest comment on your blog post: https://thinkinator.com/2016/01/12/r-users-will-now-inevitably-become-bayesians/."}}
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