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perc <- rep(-99,length(score)) a <- rep(-99,length(score)) ict <- 0 b <- duplicated(score) ict <- ict+1 |
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if (b[i] == FALSE) { ict <- ict+1 a[ict] <- score[ict] } |
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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
perc <- rep(-99,length(score)) a <- rep(-99,length(score)) ict <- 0 b <- duplicated(score) ict <- ict+1 for (i in score) { perc[i] <- 100*sum(score<=i)/length(score) if (b[i] == FALSE) { ict <- ict+1 a[ict] <- score[ict] } } perc a