ILS (version 0.3)

cochran.test: Function to compute the Cochran test statistic

Description

Function to estimate the Cochran test statistic.

Usage

cochran.test(x, ...)
# S3 method for default
cochran.test(
  x,
  var.index = 1,
  replicate.index = 2,
  material.index = 3,
  laboratory.index = 4,
  data.name = NULL,
  alpha = 0.05,
  ...
)
# S3 method for lab.qcdata
cochran.test(x, alpha = 0.05, ...)

Arguments

x

An object of class lab.qcdata (Univariate Quality Control Data).

...

Other arguments passed to or from methods.

var.index

A scalar with the column number corresponding to the observed variable (the critical to quality variable). Alternativelly can be a string with the name of the quality variable.

replicate.index

A scalar with the column number corresponding to the index each replicate.

material.index

A scalar corresponding to the replicated number.

laboratory.index

A scalar that defines the index number of each laboratory.

data.name

A string specifying the name of the variable which appears on the plots. If name is not provided, it is taken from the object given as data.

alpha

The significance level (0.05 by default)

References

Wilrich Peter-T. (2013), Critical values of mandel's h and k, the grubbs and the Cochran test statistic. Asta-Advances in Statistical Analysis, 97(1):1-10.

ASTM E 691 (1999), Standard practice for conducting an interlaboratory study to determine the precision of a test method. American Society for Testing and Materials. West Conshohocken, PA, USA.

Examples

library(ILS)
data(Glucose)
Glucose.qcdata <- lab.qcdata(Glucose)
str(Glucose.qcdata)
cochran.test(Glucose.qcdata)