如何在R中设置alpha？

Question

我有这个例子来自R的硬币包：

  library(coin)
  library(multcomp)
  ### Length of YOY Gizzard Shad from Kokosing Lake, Ohio,
  ### sampled in Summer 1984, Hollander & Wolfe (1999), Table 6.3, page 200
  YOY <- data.frame(length = c(46, 28, 46, 37, 32, 41, 42, 45, 38, 44, 
                               42, 60, 32, 42, 45, 58, 27, 51, 42, 52, 
                               38, 33, 26, 25, 28, 28, 26, 27, 27, 27, 
                               31, 30, 27, 29, 30, 25, 25, 24, 27, 30),
                    site = factor(c(rep("I", 10), rep("II", 10),
                                    rep("III", 10), rep("IV", 10))))

  ### Nemenyi-Damico-Wolfe-Dunn test (joint ranking)
  ### Hollander & Wolfe (1999), page 244 
  ### (where Steel-Dwass results are given)
  NDWD <- oneway_test(length ~ site, data = YOY,
      ytrafo = function(data) trafo(data, numeric_trafo = rank),
      xtrafo = function(data) trafo(data, factor_trafo = function(x)
          model.matrix(~x - 1) %*% t(contrMat(table(x), "Tukey"))),
      teststat = "max", distribution = approximate(B = 90000))

  ### global p-value
  print(pvalue(NDWD))

  ### sites (I = II) != (III = IV) at alpha = 0.01 (page 244)
  print(pvalue(NDWD, method = "single-step"))

我想为 alpha 分配不同的值，我该怎么做？

这不行！

  library(coin)
  library(multcomp)
  ### Length of YOY Gizzard Shad from Kokosing Lake, Ohio,
  ### sampled in Summer 1984, Hollander & Wolfe (1999), Table 6.3, page 200
  YOY <- data.frame(length = c(46, 28, 46, 37, 32, 41, 42, 45, 38, 44, 
                               42, 60, 32, 42, 45, 58, 27, 51, 42, 52, 
                               38, 33, 26, 25, 28, 28, 26, 27, 27, 27, 
                               31, 30, 27, 29, 30, 25, 25, 24, 27, 30),
                    site = factor(c(rep("I", 10), rep("II", 10),
                                    rep("III", 10), rep("IV", 10))))

  ### Nemenyi-Damico-Wolfe-Dunn test (joint ranking)
  ### Hollander & Wolfe (1999), page 244 
  ### (where Steel-Dwass results are given)
  NDWD <- oneway_test(length ~ site, data = YOY,
      ytrafo = function(data) trafo(data, numeric_trafo = rank),
      xtrafo = function(data) trafo(data, factor_trafo = function(x)
          model.matrix(~x - 1) %*% t(contrMat(table(x), "Tukey"))),
      teststat = "max", distribution = approximate(B = 90000),
      alpha = 0.05)

  ### global p-value
  print(pvalue(NDWD))

  ### sites (I = II) != (III = IV) at alpha = 0.05 (default was 0.01) (page 244)
  print(pvalue(NDWD, method = "single-step"))

Answer 1

alpha 级别是硬编码的，固定为 0.99。如果您想更改它，则必须下载包源代码，更改级别并编译包。 这些级别在Methods.R 文件中进行编码。 搜索 binom.test 或 conf.level

您可以要求包作者更改包，以便您可以自己设置级别。 但请记住，包作者没有义务这样做！

Answer 2

看起来你不能：oneway_test()没有参数conf.level，而wilcox_test和normal_test有。 这些都已记录在案，请参阅help(oneway_test)。