|
Size: 424
Comment:
|
← Revision 21 as of 2013-03-08 10:17:13 ⇥
Size: 774
Comment: converted to 1.6 markup
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 6: | Line 6: |
| Percentile (score) = 100$$\frac{n \leq score}{N}$$ | Percentile (score) = 100 $$\frac{\mbox{n} \leq \mbox{score}}{\mbox{N}}$$ |
| Line 8: | Line 8: |
| 1 - Percentile (score) = 100$$\frac{n \gt score}{N}$$ | 100 - Percentile (score) = 100 $$\frac{\mbox{n} \gt \mbox{score}}{\mbox{N}}$$ |
| Line 10: | Line 10: |
| The percentiles for each score are routinely outputted using the frequency procedure in SPSS. | The score percentiles can be obtained by running the below in SPSS. |
| Line 17: | Line 17: |
| or the below in R: {{{ score <- sort(score) perc <- rep(-99,length(score)) ict <- 1 b <- duplicated(score) for (ict in 1:length(score) { for (i in score) { perc[ict] <- 100*sum(score<=i)/length(score) ict <- ict+1 } } (percu <- perc[!duplicated(perc)]) (scoreu <- score[!duplicated(score)]) percu scoreu }}} |
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 score percentiles can be obtained by running the below in SPSS.
FREQUENCIES VAR=SCORE. EXE.
or the below in R:
score <- sort(score)
perc <- rep(-99,length(score))
ict <- 1
b <- duplicated(score)
for (ict in 1:length(score) {
for (i in score) {
perc[ict] <- 100*sum(score<=i)/length(score)
ict <- ict+1
}
}
(percu <- perc[!duplicated(perc)])
(scoreu <- score[!duplicated(score)])
percu
scoreu