Function of qnorm() in R

r normal-distribution
timeschange picture timeschange · May 18, 2016 · Viewed 14.8k times · Source

I have read the documentation on qnorm() but could not really understand what it does. Can you please answer in detail what qnorm() does?

note-Please excuse me for asking such a simple question. I am a beginner at R.

Answer

tomp picture tomp · May 18, 2016

The function qnorm() aims to find the boundary value, A in P(X < A), given the probability P.

For example, suppose you want to find the 85th percentile of a normal distribution whose mean is 70 and whose standard deviation is 3. Then you ask for:

qnorm(0.85,mean=70,sd=3)
[1] 73.1093

From https://cran.r-project.org/web/packages/tigerstats/vignettes/qnorm.html

Related questions

Perform a Shapiro-Wilk Normality Test

I want to perform a Shapiro-Wilk Normality Test test. My data is csv format. It looks like this: heisenberg HWWIchg 1 -15.60 2 -21.60 3 -19.50 4 -19.10 5 -20.90 6 -20.70 7 -19.30 8 -18.30 9 -15.10 However, when I perform the test, I get: shapiro.test(heisenberg) …

Read More
Seeing if data is normally distributed in R

Can someone please help me fill in the following function in R: #data is a single vector of decimal values normally.distributed <- function(data) { if(data is normal) return(TRUE) else return(NO) }

Read More
Generate matrix with iid normal random variables using R

Is there a way to generate a data set with normally distributed random values in R without using a loop? Each entry would represent an independent random variable with a normal distribution.

Read More