{"action":"closed","issue":{"url":"https://api.github.com/repos/brianstock/MixSIAR/issues/93","repository_url":"https://api.github.com/repos/brianstock/MixSIAR","labels_url":"https://api.github.com/repos/brianstock/MixSIAR/issues/93/labels{/name}","comments_url":"https://api.github.com/repos/brianstock/MixSIAR/issues/93/comments","events_url":"https://api.github.com/repos/brianstock/MixSIAR/issues/93/events","html_url":"https://github.com/brianstock/MixSIAR/issues/93","id":192061848,"number":93,"title":"Why the unknownGroups.R. function does not require a matrix of isotope fractionation values for each of the sources used in the mixing model?","user":{"login":"pablojorgensen","id":19475920,"avatar_url":"https://avatars.githubusercontent.com/u/19475920?v=3","gravatar_id":"","url":"https://api.github.com/users/pablojorgensen","html_url":"https://github.com/pablojorgensen","followers_url":"https://api.github.com/users/pablojorgensen/followers","following_url":"https://api.github.com/users/pablojorgensen/following{/other_user}","gists_url":"https://api.github.com/users/pablojorgensen/gists{/gist_id}","starred_url":"https://api.github.com/users/pablojorgensen/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/pablojorgensen/subscriptions","organizations_url":"https://api.github.com/users/pablojorgensen/orgs","repos_url":"https://api.github.com/users/pablojorgensen/repos","events_url":"https://api.github.com/users/pablojorgensen/events{/privacy}","received_events_url":"https://api.github.com/users/pablojorgensen/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":1,"created_at":"2016-11-28T17:08:50Z","updated_at":"2016-11-29T18:47:36Z","closed_at":"2016-11-29T18:47:36Z","body":"I have an undetermined stable isotope (SI) trophic model with 2 tracers and 5 sources for a consumer (mix). To address this undetermined model I applied the mixSIR.unknownGroupsR function (http://conserver.iugo-cafe.org/user/eric.ward/Mixing%20model%20with%20unknown%20groups) to combine sources into groups and estimate the proportional contributions of the resultant grouped sources to the consumer (Ward EJ, Semmens BX, Phillips DL, et al (2011) Ecosphere 2:art19. doi: 10.1890/ES10-00190.1). Among the input data required by the R function are: a matrix with the consumer SI data (X); a matrix of raw source SI means (u); a matrix of raw SI source variances (v); and a matrix of sample sizes (k). However, the unknownGroups.R. function does not require the input of a matrix of means (and variances) isotope fractionation values (i.e. trophic fractionation or discrimination) for each of the sources used in the model, as usual in other mixing models (e.g.: mixSIR, SIAR, MixSIAR, FRUITS)."}}
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