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Dataplot Vol 2 Vol 1

REPEATABILITY STANDARD DEVIATION

Name:
    REPEATABILITY STANDARD DEVIATION (LET)
Type:
    Let Subcommand
Purpose:
    Compute the repeatability standard deviation of a variable as defined by the ASTM E 691 - 99 standard.
Description:
    The repeatability standard deviation is a core concept defined in the ASTM E 691 - 99 standard. This standard is described in detail in the following document:

      "Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method", ASTM International, 100 Barr Harbor Drive, PO BOX C700, West Conshohoceken, PA 19428-2959, USA.

    This document describes repeatability in the following way.

      Repeatability concerns the variability between independent test results obtained within a single laboratory in the shortest practical period of time by a single operator with a specific set of test apparatus using test specimens taken at random from a single quantity of homogeneous material.

    The repeatability standard deviation for a single material is computed as

      \( s_r = \sqrt{\sum_{i=1}^{p}{s_{i}^2}/p} \)

    with p and si denoting the number of laboratories and the standard deviation of the ith laboratory, respectively.

    In an interlaboratory study, the repeatability standard deviation is computed for each material.

Syntax:
    LET <par> = REPEATABILITY STANDARD DEVIATION <y> <labid>
                            <SUBSET/EXCEPT/FOR qualification>
    where <y> is a response variable;
                <labid> is a lab-id variable;
                <par> is a parameter where the repeatability sd value is saved;
    and where the <SUBSET/EXCEPT/FOR qualification> is optional.
Examples:
    LET RSD = REPEATABILITY STANDARD DEVIATION Y LAB
    LET RSD = REPEATABILITY STAND DEVI Y LAB SUBSET MAT = 1
Note:
    The repeatability standard deviation can be computed for multiple materials with the command

      TABULATE REPEATABILITY STAND DEVI Y LABID MATID

    The repeatability standard deviation can be plotted for multiple materials with the command

      REPEATABILITY STANDARD DEVIATION PLOT Y LABID MATID
Default:
    None
Synonyms:
    REPEATABILITY SD
Related Commands:
    E691 INTERLAB = Perform an E691 interlab analysis.
    REPRODUCIBILITY STANDARD DEVIATION = Compute the reproducibility standard deviation.
Reference:
    "Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method", ASTM International, 100 Barr Harbor Drive, PO BOX C700, West Conshohoceken, PA 19428-2959, USA.
Applications:
    Interlaboratory Analysis
Implementation Date:
    2005/4
Program:
     
    SKIP 25
    READ GLUCOSE.DAT Y LABID MATID
    .
    LET MATDIST = DISTINCT MATID
    LET NMAT = SIZE MATDIST
    XLIMITS 1 NMAT
    MAJOR XTIC MARK NUMBER NMAT
    MINOR XTIC MARK NUMBER 0
    XTIC OFFSET 0.5 0.5
    Y1LABEL REPEATABILITY SD
    X1LABEL MATERIAL
    LINE BLANK
    CHARACTER X
    .
    REPEATABILITY SD PLOT Y LABID MATID
        
    plot generated by sample program

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Date created: 4/20/2005
Last updated: 10/07/2016

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