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| + perc[i] <- 100*sum(score<=i)/length(score) + } |
perc[i] <- 100*sum(score<=i)/length(score) unique[i] <- score[i] } |
How do I find out how many people have a score above a certain value?
Percentiles give the percentage of people who have a score below a threshold score.
Percentile (score) = 100 $$\frac{\mbox{n} \leq \mbox{score}}{\mbox{N}}$$
100 - Percentile (score) = 100 $$\frac{\mbox{n} \gt \mbox{score}}{\mbox{N}}$$
The percentiles for each score are routinely outputted using the frequency procedure in SPSS.
FREQUENCIES VAR=SCORE. EXE.
In R the percentages of people with scores equal or below each observed score can be obtained by running
> for (i in score) {
perc[i] <- 100*sum(score<=i)/length(score)
unique[i] <- score[i]
}
> perc