15 / 124
2012.20 CHOLINE MLT
LARU224 GLVC238
FOR ERP USE ONLY
DO NOT DISTRIBUTE
AOAC International Interlaboratory Study Workbook
Version:
2.1
Blind (Unpaired) Replicates
Results Sheet
Seq.
Item
Symbol
Value
Study name:
Choline 2012-20
Study date:
2015-2016
Sample ID:
LARU224/GLVC238
1 Total number of laboratories
p
11
2 Total number of replicates
Sum(n(L))
22
3 Average number of replicates per lab
Sum(n(L))/p
2.00
4 Sum of replicates squared
Sum(n(L)^2)
44
5 Sum of lab totals
Sum(Lab Totals)
97.06
6 Sum of lab averages
Sum(Lab Avg.)
48.53
7 Sum of lab totals squared/n(L)
Sum(T(L)^2/n(L))
526.66
8 Sum of squares for replicates
SSQ(devn.)
0.17
9 Sum of Squares for Labs
LSS
98.45
10 Effective mean number of reps per lab
NBAR
2.0000
11 Unweighted mean of the laboratory averages
XBAR
4.4118
12 Overall mean of all data (grand mean)
XBARBAR
4.4118
13 Repeatability variance
s(r)^2
0.0155
14 Repeatability standard deviation
s(r)
0.1247
15 "Pure" among laboratories variance
s(L)^2
4.9146
16 Reproducibility variance
s(R)^2
4.9301
17 Reproducibility standard deviation
s(R)
2.2204
18 Repeatability relative standard deviation
RSD(r)
2.83
19 Reproducibility relative standard deviation
RSD(R)
50.33
20 Repeatability value = 2.8*s(r)
r
0.349
21 Reproducibility value = 2.8*s(R)
R
6.217
22 HORRAT value
5.56
Record these values for Results
Number of Laboratories
11
Largest within variance
0.0800
Largest average lab result
10.2000
Smallest average lab result
2.2500
If proportion of labs removed from the total is less than 2/9, then
Cochran's Test =
46.8%
Critical value, 2.5% significance =
62.2%
Result =
Not significant
with maximum within lab variance for
Lab 10
If Cochran test is not significant, then proceed
Single Grubb's Test =
47.2%
Critical value, 2.5% significance =
38.8%
Result =
Significant!
highest average at
Lab 10
gives % decrease in standard deviation =
47.2%
lowest average at
Lab 11
gives % decrease in standard deviation =
0.2%
If Single Grubb's test is not significant, then proceed
Double Grubb's Test =
60.5%
Critical value, 2.5% significance =
52.1%
Result =
Significant!
Excluding the highest avg. and next highest avg
gives % decrease in standard deviation =
60.5%
Excluding the lowest avg. and next lowest avg
gives % decrease in standard deviation =
1.0%
Excluding the highest avg. and lowest avg
gives % decrease in standard deviation =
50.7%