So … I'd like to know which IQ score (sd=15) corresponds to a given percentile.

The straigtforward way in R is to ask


Where percentile is between 0 and 100 and sample is a very large number. Occasionally, not large enough for sufficient accuracy.

Does R have a more accurate algorithm? I've googled, and found math that's over my head to the extent that I can't turn it into R code.

Any and all hints and suggestions appreciated.

Thank you.


closed as off-topic by Peter Flom Jul 14 '18 at 12:07

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qnorm is your friend.

For example 50th and 90th percentiles:

[1] 100

[1] 119,2233

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