http://commres.net/ 2026-04-04T09:58:41+00:00 http://commres.net/ http://commres.net/_media/wiki/logo.png text/html 2025-12-02T23:51:50+00:00 Anonymous (anonymous@undisclosed.example.com) http://commres.net/c/ps1/2025/t-test_note/code01?rev=1764719510&do=diff ### rnorm2 <- function(n,mean,sd) { mean+sd*scale(rnorm(n)) } groupA <- rnorm2(10, 19, sqrt(160/9)) groupB <- rnorm2(10, 25, sqrt(200/9)) ss.a <- 160 ss.b <- 200 n.a <- 10 n.b <- 10 df.a <- 9 df.b <- 9 pooled.v <- (ss.a+ss.b)/(df.a+df.b) pooled.v se <- sqrt(pooled.v/n.a + pooled.v/n.b) se diff <- (mean(groupA)-mean(groupB)) t.cal <- diff/se t.cal pt(t.cal, df=df.a+df.b)*2 t.test(groupA, groupB, var.equal=T) # 만약에 정확한 구간의 probability 보다 # 95% confidence interval의 점수를 구하고 # 싶다면 t.critica… text/html 2025-12-02T23:51:23+00:00 Anonymous (anonymous@undisclosed.example.com) http://commres.net/c/ps1/2025/t-test_note/output01?rev=1764719483&do=diff > ### > rnorm2 <- function(n,mean,sd) { + mean+sd*scale(rnorm(n)) + } > groupA <- rnorm2(10, 19, sqrt(160/9)) > groupB <- rnorm2(10, 25, sqrt(200/9)) > ss.a <- 160 > ss.b <- 200 > n.a <- 10 > n.b <- 10 > df.a <- 9 > df.b <- 9 > pooled.v <- (ss.a+ss.b)/(df.a+df.b) > pooled.v [1] 20 > se <- sqrt(pooled.v/n.a + pooled.v/n.b) > se [1] 2 > diff <- (mean(groupA)-mean(groupB)) > t.cal <- diff/se > t.cal [1] -3 > pt(t.cal, df=df.a+df.b)*2 [1] 0.007685412 > > t.test(groupA, groupB, var.equal=T) …