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Dataplot Vol 1 Auxiliary Chapter

CONSENSUS MEAN PLOT

Name:
    CONSENSUS MEAN PLOT
Type:
    Graphics Command
Purpose:
    Compute an estimate of a consensus mean, and the associated uncertainty, based on the data from multiple laboratories or multiple methods and present the results in a graphical format.
Description:
    The problem of determining a consensus mean based on the data from two or more laboratories (or from using two or more methods from the same laboratory) is a common one at NIST and other measurement laboratories. There are a number of approaches to this problem. The Dataplot CONSENSUS MEANS command implements a number of the more commonly used approaches. Note that Dataplot computes estimates for a variety of methods and does not specify which is the most appropriate method for a given data set. Consult with a statistician for guidance on which method is most appropriate for your data.

    The CONSENSUS MEAN PLOT command presents the results for a consensus means analysis and presents the results in a grapical format. This is useful for comparing the results generated by the different methods. It effectively performs the identifical analysis as the CONSENSUS MEANS command, but then goes one step further and displays the estimated mean, the lower uncertainty interval, and the upper uncertainty interval generated for each of the methods. For a description of the methods supported by Dataplot, enter

      HELP CONSENSUS MEANS

    The methods are plotted in the following order:

    1. Global mean (t statistic using all the data)
    2. Mandel-Paule
    3. Modified Mandel-Paule
    4. Vangel-Ruhkin (maximum likelihood)
    5. Mean of means
    6. Schiller-Eberhardt
    7. Bounds on bias (BOB) (this method is omitted for more than 5 labs)
Syntax:
    CONSENSUS MEAN PLOT <y> <tag> <SUBSET/EXCEPT/FOR qualification>
    where <y> is the response variable;
    <tag> is the group-id variable;
    and where the <SUBSET/EXCEPT/FOR qualification> is optional.
Examples:
    CONSENSUS MEAN PLOT Y X
    CONSENSUS MEAN PLOT Y TAG
    CONSENSUS MEAN PLOT Y TAG SUBSET TAG >= 2
    CONSENSUS MEAN PLOT Y TAG SUBSET TAG = 1 TO 6
Note:
    You can use the CHARACTER and LINE commands to control the appearance of the plot. Specifically,

    1. Trace 1 is a line connecting the estimated means for each of the methods.
    2. Traces 2, 3, and 4 are the estimated means, lower interval, and upper interval, respectively, within a given method.
    3. Trace 5 is line connecting the lower and upper interval within a single method.
    This is demonstrated in the example program below.
Default:
    None
Synonyms:
    There are no synonyms for this command.
Related Commands:
    CONSENSUS MEANS = Perform a consensus means analysis.
    BOX PLOT = Generate a box plot.
    MEAN PLOT = Generate a mean plot.
    SD PLOT = Generate a standard deviation plot.
    YOUDEN PLOT = Generate a Youden plot.
    ANOVA = Perform an analysis of variance.
Reference:
    Andrew Ruhkin and Mark Vangel, "Estimation of a Common Mean and Weighted Means Statistics", Journal of the American Statistical Association, March, 1998, Vol. 93, No. 441.

    Mark Vangel and Andrew Ruhkin, "Maximum Likelihjood Analysis for Heteroscedastic One-Way Random Effects ANOVA in Interlaboratory Studies", Biometrics 55, 129-136, March 1999.

    "An ISO GUM Approach to Combining Results from Multiple Methods", M. S. Levenson, D. L. Banks, K. R. Eberhardt, L. M. Gill, W. F. Guthrie, H. K. Liu, M. G. Vangel, J. H. Yen, and N. F. Zhang, Journal of Research of the National Institute of Standards and Technology, Volume 105, Number 4, July-August 2000.

    Susannah Schiller and Keith Eberhardt, "Combining Data from Independent Analysis Methods", Spectrochim, ACTA 46 (12), 1991.

    Susannah Schiller , "Standard Reference Materials: Statistical Aspects of the Certification of Chemical SRMs", NIST SP 260-125, NIST, Gaithersburg, MD, 1996.

Applications:
    Standard Reference Materials, Interlaboratory Studies
Implementation Date:
    2001/8
Program:
    SKIP 25
    READ STUTZ86.DAT ALITE JUNK2 JUNK3 JUNK4 JUNK5 LABID
    .
    CHARACTER FONT SIMPLEX ALL
    CHARACTER SIZE 4 ALL
    CHARACTER BLANK HBAR HBAR HBAR BLANK
    LINE DOTTED BLANK BLANK BLANK SOLID
    .
    LABEL CASE ASIS
    TIC MARK LABEL CASE ASIS
    Y1LABEL Consensus Mean
    XLIMITS 1 7
    MAJOR XTIC MARK NUMBER 7
    MINOR XTIC MARK NUMBER 0
    XTIC OFFSET 0.5 0.5
    X1TIC MARK LABEL FORMAT ALPHA
    X1TIC MARK LABEL CONTENT Globalcr()Mean MP Modifiedcr()MP ...
    ML Meansp()ofcr()Means Schiller-cr()Eberhardt BOB
    X3LABEL Estimation Method
    TITLE AUTOMATIC
    .
    CONSENSUS MEAN PLOT ALITE LABID

    plot generated by sample program

Date created: 8/17/2001
Last updated: 4/4/2003
Please email comments on this WWW page to alan.heckert@nist.gov.