# 3.5.3.1.26 QCD4

## Description

This function returns a factor. (Quality Control D4 Factor)

It determines the 3-sigma upper control limit for R charts (Range of Sample Charts) from the average range when the sample size (or subgroup size) n is given.

The Upper Control Limit for R = (factor)*(Average Range).

The calculations for the factors are based on the normal distribution.

## Syntax

double QCD4(int n)

n

Sample size

## Return

Returns Quality Control D4 Factor

## Examples

QCD4(11) =; //returns 1.744, the Quality Control D4 factor for a sample size of 11