CONSENSUS MEAN PLOT
Name:
Type:
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
The methods are plotted in the following order:
- Global mean (t statistic using all the data)
- Mandel-Paule
- Modified Mandel-Paule
- Vangel-Ruhkin (maximum likelihood)
- Mean of means
- Schiller-Eberhardt
- 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,
- Trace 1 is a line connecting the estimated means for
each of the methods.
- Traces 2, 3, and 4 are the estimated means, lower interval,
and upper interval, respectively, within a given method.
- Trace 5 is line connecting the lower and upper interval
within a single method.
This is demonstrated in the example program below.
Default:
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:
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
Date created: 8/17/2001
Last updated: 4/4/2003
Please email comments on this WWW page to
alan.heckert@nist.gov.
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