qnormGC: Graphical Calculator for Normal Curve Percentiles

In tigerstats: R Functions for Elementary Statistics

Description

When you know a certain area under a normal density curve, this function returns the x-axis values of the boundary of that area.

Usage

qnormGC(area,region="below",mean=0,sd=1,graph=FALSE)

Arguments

area	The known percentile
region	A character string. Default is "below". Other possible values are "between" (when known area is symmetric around the mean two numbers), "below", "above", and "outside" (when known area is outside a region symmetric around the mean)
mean	Mean of the distribution
sd	Standard deviation of the distribution
graph	Will produce graph of the area

Value

Numerical value of the percentile, and a vector when there are two bounds.

Author(s)

Homer White [e-mail]

Examples

#80th percentile of a normal distribution with mean=70 and sd=4:
qnormGC(0.80,region="below",mean=70,sd=4)

#Return value x so that P(X > x) = 0.10 (same as the 90th percentile)
qnormGC(0.10,region="above",mean=70,sd=4)

#This gives the multiplier for 95%-confidence intervals based on the z-statistic
qnormGC(0.95,region="between")

#This gives critical values for a two-sided z-test with alpha = 0.01:
qnormGC(0.01,region="outside")

Example output

Loading required package: abd
Loading required package: nlme
Loading required package: lattice
Loading required package: grid
Loading required package: mosaic
Loading required package: dplyr

Attaching package: 'dplyr'

The following object is masked from 'package:nlme':

    collapse

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Loading required package: ggformula
Loading required package: ggplot2

New to ggformula?  Try the tutorials: 
	learnr::run_tutorial("introduction", package = "ggformula")
	learnr::run_tutorial("refining", package = "ggformula")
Loading required package: mosaicData
Loading required package: Matrix

The 'mosaic' package masks several functions from core packages in order to add 
additional features.  The original behavior of these functions should not be affected by this.

Note: If you use the Matrix package, be sure to load it BEFORE loading mosaic.

Attaching package: 'mosaic'

The following object is masked from 'package:Matrix':

    mean

The following objects are masked from 'package:dplyr':

    count, do, tally

The following objects are masked from 'package:stats':

    IQR, binom.test, cor, cor.test, cov, fivenum, median, prop.test,
    quantile, sd, t.test, var

The following objects are masked from 'package:base':

    max, mean, min, prod, range, sample, sum

Welcome to tigerstats!
To learn more about this package, consult its website:
	http://homerhanumat.github.io/tigerstats
[1] 73.36648
[1] 75.12621
[1] -1.959964  1.959964
[1] -2.575829  2.575829

tigerstats documentation built on July 2, 2020, 2:32 a.m.