{"id":3194,"date":"2015-07-30T09:59:32","date_gmt":"2015-07-30T08:59:32","guid":{"rendered":"https:\/\/abcdr.guyader.pro\/?p=3194"},"modified":"2018-04-08T00:02:25","modified_gmt":"2018-04-07T23:02:25","slug":"comment-utiliser-la-lois-gamma-sur-r","status":"publish","type":"post","link":"https:\/\/thinkr.fr\/abcdr\/comment-utiliser-la-lois-gamma-sur-r\/","title":{"rendered":"Comment utiliser la Lois Gamma sur R ?"},"content":{"rendered":"

La loi Gamma ou d\u2019Euler<\/a>\u00a0est une loi tr\u00e8s utiles pour les propri\u00e9t\u00e9s de d\u00e9croissance rapide.\u00a0La loi Gamma peut d\u00e9crire des ph\u00e9nom\u00e8nes de dur\u00e9e de vie, pour l\u2019\u00e9tude du temps \u00e9coul\u00e9 entre deux faits.<\/p>\n

\u00a0<\/p>\n

Sur R, les options\u00a0shape\u00a0et\u00a0scale\u00a0correspondent respectivement\u00a0\u03b1\u00a0et\u00a0\u03b2.<\/p>\n

Nous pouvons calculer la densit\u00e9 de probabilit\u00e9 de la loi G(1,3) pour la valeur x=2\u00a0gr\u00e2ce \u00e0 la fonction\u00a0dgamma()\u00a0:<\/b><\/p>\n

\n\nX<-2
alpha<-1
beta<-3\n\ndgamma(x,shape=alpha,scale=beta)\n\n<\/code><\/pre>\n
\u00a0\u00a0<\/p>\n
Nous pouvons calculer la probabilit\u00e9 que x soit inf\u00e9rieur ou \u00e9gal \u00e0 2\u00a0sur la loi G(1,3), c\u2019est-\u00e0-dire calculer la fonction de r\u00e9partition F(2)\u00a0gr\u00e2ce \u00e0 la fonction\u00a0pgamma()\u00a0:<\/b><\/p>\n
\n\nX<-2
alpha<-1
beta<-3\n\npgamma(x,shape=alpha,scale=beta)\n\n<\/code><\/pre>\n
\u00a0\u00a0\u00a0<\/p>\n
Nous pouvons \u00e9galement calculer la probabilit\u00e9 que x soit sup\u00e9rieur \u00e0 2\u00a0sur la loi G(1,3)\u00a0:<\/b><\/p>\n
\n\nX<-2
alpha<-1
beta<-3\n\npgamma(x,shape=alpha,scale=beta, lower.tail=FALSE)\n\n<\/code><\/pre>\n
\u00a0\u00a0\u00a0<\/p>\n
Nous pouvons calculer le seuil de x correspondant aux 2.5% plus hautes valeurs de x, c\u2019est-\u00e0-dire F(xi) = 0.025. Pour cela nous utilisons la fonction\u00a0qgamma()\u00a0:<\/b><\/p>\n
\n\nX<-2
alpha<-1
beta<-3\n\nqgamma(x,shape=alpha,scale=beta, lower.tail=FALSE)\n\n<\/code><\/pre>\n
\u00a0\u00a0<\/p>\n
Il est possible de r\u00e9aliser des simulations d\u2019une loi Gamma gr\u00e2ce \u00e0 la fonction\u00a0rgamma<\/b><\/a>().<\/p>\n","protected":false},"excerpt":{"rendered":"
La loi Gamma ou d\u2019Euler\u00a0est une loi tr\u00e8s utiles pour les propri\u00e9t\u00e9s de d\u00e9croissance rapide.\u00a0La loi Gamma peut d\u00e9crire des ph\u00e9nom\u00e8nes de dur\u00e9e de vie, pour l\u2019\u00e9tude du temps \u00e9coul\u00e9 entre deux faits. \u00a0 Sur R, les options\u00a0shape\u00a0et\u00a0scale\u00a0correspondent respectivement\u00a0\u03b1\u00a0et\u00a0\u03b2. Nous pouvons calculer la densit\u00e9 de probabilit\u00e9 de la loi G(1,3) pour la valeur x=2\u00a0gr\u00e2ce \u00e0 la fonction\u00a0dgamma()\u00a0: X<-2alpha<-1beta<-3 dgamma(x,shape=alpha,scale=beta) \u00a0\u00a0 Nous pouvons calculer la probabilit\u00e9 que x soit inf\u00e9rieur ou \u00e9gal \u00e0 2\u00a0sur la loi G(1,3), c\u2019est-\u00e0-dire calculer la fonction de r\u00e9partition F(2)\u00a0gr\u00e2ce \u00e0 la fonction\u00a0pgamma()\u00a0: X<-2alpha<-1beta<-3 pgamma(x,shape=alpha,scale=beta) \u00a0\u00a0\u00a0 Nous pouvons \u00e9galement calculer la probabilit\u00e9 que x soit sup\u00e9rieur \u00e0 2\u00a0sur la loi G(1,3)\u00a0: X<-2alpha<-1beta<-3Read More →<\/a><\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"content-type":"","rop_custom_images_group":[],"rop_custom_messages_group":[],"rop_publish_now":"initial","rop_publish_now_accounts":{"twitter_399453572_399453572":""},"rop_publish_now_history":[],"rop_publish_now_status":"pending","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[8],"tags":[],"class_list":{"0":"entry","1":"post","2":"publish","3":"author-helene","4":"post-3194","6":"format-standard","7":"category-fonctions-utiles"},"acf":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p9O7Sx-Pw","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/posts\/3194","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/comments?post=3194"}],"version-history":[{"count":2,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/posts\/3194\/revisions"}],"predecessor-version":[{"id":4301,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/posts\/3194\/revisions\/4301"}],"wp:attachment":[{"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/media?parent=3194"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/categories?post=3194"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thinkr.fr\/abcdr\/wp-json\/wp\/v2\/tags?post=3194"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}