列上的多个 t 检验答案

【问题标题】：Multiple t-tests over columns列上的多个 t 检验
【发布时间】：2021-02-27 00:44:23
【问题描述】：

我对 R 还是很陌生。

data.frame(treatment = c("D", "E", "F", "G"), group = c(rep(c("A", "B"), each = 4)), 
           effect = c(1, 4, 5, 6, 8, 9, 10, 11))


    treatment group effect
1         D     A      1
2         E     A      4
3         F     A      5
4         G     A      6
5         D     B      8
6         E     B      9
7         F     B     10
8         G     B     11

对于治疗中的每个条目，我想使用 t 检验来查看两组的效果是否存在统计学上的显着差异。

非常感谢！

【问题讨论】：

对于给定治疗的每种效果，您只有一个观察值。无法使用该数据执行t.test。我错过了什么吗？

标签： r lapply t-test

【解决方案1】：

使用by。

by(d, d$treatment, function(x) with(x, t.test(effect ~ group)))
# d$treatment: A
# 
# Welch Two Sample t-test
# 
# data:  effect by group
# t = -1.941, df = 2.6904, p-value = 0.1581
# alternative hypothesis: true difference in means is not equal to 0
# 95 percent confidence interval:
#   -16.510018   4.510018
# sample estimates:
#   mean in group A mean in group B 
# 4.333333       10.333333 
# 
# -------------------------------------------------------- 
#   d$treatment: B
# 
# Welch Two Sample t-test
# 
# data:  effect by group
# t = -3.1623, df = 3.4483, p-value = 0.04191
# alternative hypothesis: true difference in means is not equal to 0
# 95 percent confidence interval:
#   -6.4542173 -0.2124494
# sample estimates:
#   mean in group A mean in group B 
# 4.000000        7.333333

数据：

我制作了新的示例数据，因为您的数据似乎有缺陷。

d <- structure(list(treatment = c("A", "B", "A", "B", "A", "B", "A", 
"B", "A", "B", "A", "B"), group = c("A", "A", "B", "B", "A", 
"A", "B", "B", "A", "A", "B", "B"), effect = c(1L, 5L, 12L, 9L, 
2L, 4L, 8L, 6L, 10L, 3L, 11L, 7L)), out.attrs = list(dim = c(treatment = 2L, 
group = 2L, id = 3L), dimnames = list(treatment = c("treatment=A", 
"treatment=B"), group = c("group=A", "group=B"), id = c("id=1", 
"id=2", "id=3"))), row.names = c(NA, -12L), class = "data.frame")

d
#    treatment group effect
# 1          A     A      1
# 2          B     A      5
# 3          A     B     12
# 4          B     B      9
# 5          A     A      2
# 6          B     A      4
# 7          A     B      8
# 8          B     B      6
# 9          A     A     10
# 10         B     A      3
# 11         A     B     11
# 12         B     B      7

【讨论】：