#Setup some dummy data
set.seed(1234)
numSubjects <- 20
subject <- 1:numSubjects
before <- runif(numSubjects)
after <- before - 0.35*runif(length(before))
df <- data.frame(
subject=rep(subject,2),
group=c(
rep("before",numSubjects),
rep("after",numSubjects)
),
value=c(before, after)
)
##################################
valueBefore <- df[df$group == "before",]$value
valueAfter <- df[df$group == "after",]$value
# d1 == d2
d1 <- effsize::cohen.d(valueAfter, valueBefore, paired=T)
d2 <- effsize::cohen.d(value~group, data=df, paired=T)
##################################
# Sorted by subjectId
df <- df[order(df$subject),]
valueBefore <- df[df$group == "before",]$value
valueAfter <- df[df$group == "after",]$value
# d1==d2==d3 is the same: d estimate: -0.5307307 (medium)
# but d4 is not: -0.145407 (negligible)
d3 <- effsize::cohen.d(valueAfter, valueBefore, paired=T)
d4 <- effsize::cohen.d(value~group, data=df, paired=T)
##################################
# Sorted by group
df <- df[order(df$group),]
valueBefore <- df[df$group == "before",]$value
valueAfter <- df[df$group == "after",]$value
# d1 == d2 == d3 == d5 == d6 are the same (although still false due to #49)
d5 <- effsize::cohen.d(valueAfter, valueBefore, paired=T)
d6 <- effsize::cohen.d(value~group, data=df, paired=T)
##################################
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