acat(VGAM)
acat()所属R语言包：VGAM
Ordinal Regression with Adjacent Categories Probabilities
序回归与相邻品类的概率
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Fits an adjacent categories regression model to an ordered (preferably) factor response.
适用于相邻品类的回归模型的有序（最好）因子反应。
用法----------Usage----------
acat(link = "loge", earg = list(),
parallel = FALSE, reverse = FALSE, zero = NULL,
whitespace = FALSE)
参数----------Arguments----------
参数：link
Link function applied to the ratios of the adjacent categories probabilities. See Links for more choices.
Link功能施加到相邻的类别的概率的比率。见Links更多的选择。
参数：earg
List. Extra argument for the link function. See CommonVGAMffArguments for more information.
列表。额外的参数的链接功能。见CommonVGAMffArguments更多信息。
参数：parallel
A logical, or formula specifying which terms have equal/unequal coefficients.
一个逻辑，或指定的条款有平等/不平等系数，公式。
参数：reverse
Logical. By default, the linear/additive predictors used are eta_j = log(P[Y=j+1]/P[Y=j]) for j=1,…,M. If reverse is TRUE then eta_j=log(P[Y=j]/P[Y=j+1]) will be used.
逻辑。默认情况下，线性/对使用添加剂的预测是eta_j = log(P[Y=j+1]/P[Y=j])j=1,…,M。 reverse如果是TRUE然后eta_j=log(P[Y=j]/P[Y=j+1])使用。
参数：zero
An integer-valued vector specifying which linear/additive predictors are modelled as intercepts only. The values must be from the set {1,2,...,M}.
指定一个整数值向量线性/添加剂的预测模型仅作为拦截。这些值必须是集合{1,2，...，M}。
参数：whitespace
See CommonVGAMffArguments for information.
见CommonVGAMffArguments的信息。
Details
详细信息----------Details----------
In this help file the response Y is assumed to be a factor with ordered values 1,2,…,M+1, so that M is the number of linear/additive predictors eta_j.
本帮助文件中的响应Y被认为是一个因素，有序值1,2,…,M+1，使M是线性/添加剂预测eta_j。
By default, the log link is used because the ratio of two probabilities is positive.
默认情况下，log链接，是因为两个概率之比是积极的。
值----------Value----------
An object of class "vglmff" (see vglmff-class). The object is used by modelling functions such as vglm, rrvglm and vgam.
类的一个对象"vglmff"（见vglmff-class）。该对象被用于建模功能，如vglm，rrvglm和vgam。
警告----------Warning ----------
No check is made to verify that the response is ordinal; see ordered.
不进行任何检查来验证的响应顺序; ordered。
注意----------Note----------
The response should be either a matrix of counts (with row sums that are all positive), or a factor. In both cases, the y slot returned by vglm/vgam/rrvglm is the matrix of counts.
该反应应该是一个矩阵的计数（与行的款项都是正面），或一个因素。在这两种情况下，y返回vglm插槽/vgam/rrvglm是矩阵的计数。
For a nominal (unordered) factor response, the multinomial logit model (multinomial) is more appropriate.
对于标称值（无序的）因素的反应，多项式Logit模型（multinomial）是比较合适的。
Here is an example of the usage of the parallel argument. If there are covariates x1, x2 and x3, then parallel = TRUE ~ x1 + x2 -1 and parallel = FALSE ~ x3 are equivalent. This would constrain the regression coefficients for x1 and x2 to be equal; those of the intercepts and x3 would be different.
下面是一个例子parallel参数的使用。如果有协变量x1，x2和x3，那么parallel = TRUE ~ x1 + x2 -1和parallel = FALSE ~ x3是等效的。这将限制的回归系数x1和x2是相等的;的拦截和x3会有所不同。
（作者）----------Author(s)----------
Thomas W. Yee
参考文献----------References----------
Categorical Data Analysis, 2nd ed. New York: Wiley.
Analyzing Categorical Data, New York: Springer-Verlag.
The <code>VGAM</code> package for categorical data analysis. Journal of Statistical Software, 32, 1–34. http://www.jstatsoft.org/v32/i10/.
http://www.stat.auckland.ac.nz/~yee contains further information and examples.
参见----------See Also----------
cumulative, cratio, sratio, multinomial, pneumo.
cumulative，cratio，sratio，multinomial，pneumo。
实例----------Examples----------
pneumo <- transform(pneumo, let = log(exposure.time))
(fit <- vglm(cbind(normal,mild,severe) ~ let, acat, pneumo))
coef(fit, matrix = TRUE)
constraints(fit)
model.matrix(fit)
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
注3：如遇到不准确之处，请在本贴的后面进行回帖，我们会逐渐进行修订。
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发表于 2012-10-1 15:24:20
