英文:
Why do I have different p-values if calculated differently?
问题
以下是您要翻译的内容：
我确实有以下的数据框：df <- data.frame(Assay = c("Gene1", "Gene2", "Gene3"),DT1 = c(1,2,3),DT2 = c(4,5,6),DT3 = c(4,5,6),DT4 = c(0,8,7),DT5 = c(-1,2,5),DT6 = c(4,5,3),DT7 = c(5,2,9),DT8 = c(0,0,4),DT9 = c(3,6,2),DT10 = c(5,9,1),DT11 = c(2,3,4),DT12 = c(8,1,6))并且我想要创建一个包含逐行比较的组的p值的列。前5列（2:6）与接下来的7列（7:13）：# 逐行执行t检验并获取p值p_values <- apply(df[, 2:6], 1, function(row) {t_test_result <- t.test(row, df[, 7:13])t_test_result$p.value})# 将p值列添加到数据框中df$p_values <- p_valuesdf对于第一行，当我使用此脚本时，我得到了`0.09335115`的p值，而如果我手动执行：t.test(c(1,4,4,0,-1),c(4,5,0,3,5,2,8))我得到的p值是`0.1425`问题出在哪里？
如果您需要进一步的解释或有其他问题，请随时提出。
英文:
I do have the following dataframe:
df <- data.frame(Assay = c("Gene1", "Gene2", "Gene3"),DT1 = c(1,2,3),DT2 = c(4,5,6),DT3 = c(4,5,6),DT4 = c(0,8,7),DT5 = c(-1,2,5),DT6 = c(4,5,3),DT7 = c(5,2,9),DT8 = c(0,0,4),DT9 = c(3,6,2),DT10 = c(5,9,1),DT11 = c(2,3,4),DT12 = c(8,1,6))
And I would like to create a column that will contain p-values for groups compared row by row. First 5 columns (2:6) versus Next 7 columns (7:13)
# Perform t-tests row-wise and obtain p-valuesp_values <- apply(df[, 2:6], 1, function(row) {t_test_result <- t.test(row, df[, 7:13])t_test_result$p.value})# Add the p-values column to the dataframedf$p_values <- p_valuesdf
For the first row when I use this script I have a p-value of 0.09335115 while if I do it manually:
t.test(c(1,4,4,0,-1),c(4,5,0,3,5,2,8))
I do have a p-value of 0.1425
What's the issue?
答案1
得分: 2
只返回翻译好的部分：
只需执行：p_values <- apply(df[-1], 1, function(row) {t_test_result <- t.test(row[1:5], row[6:12])t_test_result$p.value})p_values[1] 0.1425172 0.6840726 0.3266262
英文:
just do:
p_values <- apply(df[-1], 1, function(row) {t_test_result <- t.test(row[1:5], row[6:12])t_test_result$p.value})p_values[1] 0.1425172 0.6840726 0.3266262
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