Dataplot Vol 2 Vol 1

# K CONSISTENCY STATISTIC

Name:
K CONSISTENCY STATISTIC (LET)
Type:
Let Subcommand
Purpose:
Compute the k-consistency statistic of a variable as defined by the ASTM E691 standard.
Description:
The k-consistency statistic is defined in the ASTM E691 standard as

$$k = \frac{s} {s_r}$$

with

s = cell standard deviation sr = repeatability standard deviation

Essentially, k is the ratio of the cell standard devition to the pooled value.

Syntax 1:
LET <k> = K CONSISTENCY STATISTIC <y> <labid>
<SUBSET/EXCEPT/FOR qualification>
where <y> is a response variable;
<labid> is a lab-id variable;
<k> is a variable where the k-consistency statistic values are saved; and where the <SUBSET/EXCEPT/FOR qualification> is optional.

This syntax is used to compute the k-consistency statistic for a single material. The number of k-values is equal to the number of laboratories.

Syntax 2:
LET <k> <labtag> <mattag>= K CONSISTENCY STATISTIC <y> <labid> <matid>
<SUBSET/EXCEPT/FOR qualification>
where <y> is a response variable;
<labid> is a lab-id variable;
<matid> is a material-id variable;
<h> is a variable where the k-consistency statistic values are saved;
<labtag> is a variable where the corresponding lab-id values are saved;
<mattag> is a variable where the corresponding material-id values are saved;
and where the <SUBSET/EXCEPT/FOR qualification> is optional.

This syntax is used to compute the k-consistency statistic for multiple materials. The number of k-values is equal to the number of materials times the number of laboratories.

Examples:
LET A = K CONSISTENCY STATISTIC Y LAB
LET HVAL = K CONSISTENCY STATISTIC Y LAB MAT
LET HVAL = K CONSISTENCY STATISTIC Y LAB MAT SUBSET MAT > 2
Default:
None
Synonyms:
None
Related Commands:
 E691 INTERLAB = Perform an E691 interlab analysis. K CONSISTENCY PLOT = Generate an k consistency plot. H CONSISTENCY STATISTIC = Compute the h-consistency statistic.
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
.
LET KVAL LABTAG MATTAG = K CONSISTENCY STATISTIC Y MATID LABID
.
SET WRITE DECIMALS 4
PRINT KVAL LABTAG MATTAG

The following output is generated

---------------------------------------------
KVAL         LABTAG         MATTAG
---------------------------------------------
0.2097         1.0000         1.0000
0.4562         2.0000         1.0000
0.9977         3.0000         1.0000
1.7040         4.0000         1.0000
0.3448         5.0000         1.0000
1.3244         6.0000         1.0000
1.1736         7.0000         1.0000
0.7735         8.0000         1.0000
0.1058         1.0000         2.0000
0.8876         2.0000         2.0000
0.5555         3.0000         2.0000
1.8466         4.0000         2.0000
0.5187         5.0000         2.0000
1.0948         6.0000         2.0000
1.3784         7.0000         2.0000
0.3388         8.0000         2.0000
0.2150         1.0000         3.0000
0.7889         2.0000         3.0000
0.6290         3.0000         3.0000
2.4088         4.0000         3.0000
0.4362         5.0000         3.0000
0.4683         6.0000         3.0000
0.7730         7.0000         3.0000
0.3556         8.0000         3.0000
0.0229         1.0000         4.0000
1.7837         2.0000         4.0000
0.6069         3.0000         4.0000
0.7377         4.0000         4.0000
0.7172         5.0000         4.0000
0.6284         6.0000         4.0000
1.4543         7.0000         4.0000
0.9386         8.0000         4.0000
0.1847         1.0000         5.0000
2.3347         2.0000         5.0000
0.6887         3.0000         5.0000
0.2245         4.0000         5.0000
0.2425         5.0000         5.0000
1.0252         6.0000         5.0000
0.8397         7.0000         5.0000
0.4188         8.0000         5.0000


NIST is an agency of the U.S. Commerce Department.

Date created: 04/19/2005
Last updated: 06/30/2015