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2012.20 CHOLINE MLT
YKLP059 ZNPI092
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 MLT
Study date:
2015-2016
Sample ID:
YKLP059&ZNPI092
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)
379.70
6 Sum of lab averages
Sum(Lab Avg.)
189.85
7 Sum of lab totals squared/n(L)
Sum(T(L)^2/n(L))
6655.17
8 Sum of squares for replicates
SSQ(devn.)
5.22
9 Sum of Squares for Labs
LSS
101.89
10 Effective mean number of reps per lab
NBAR
2.0000
11 Unweighted mean of the laboratory averages
XBAR
17.2591
12 Overall mean of all data (grand mean)
XBARBAR
17.2591
13 Repeatability variance
s(r)^2
0.4750
14 Repeatability standard deviation
s(r)
0.6892
15 "Pure" among laboratories variance
s(L)^2
4.8569
16 Reproducibility variance
s(R)^2
5.3319
17 Reproducibility standard deviation
s(R)
2.3091
18 Repeatability relative standard deviation
RSD(r)
3.99
19 Reproducibility relative standard deviation
RSD(R)
13.38
20 Repeatability value = 2.8*s(r)
r
1.930
21 Reproducibility value = 2.8*s(R)
R
6.465
22 HORRAT value
1.82
Record these values for Results
Number of Laboratories
11
Largest within variance
4.8050
Largest average lab result
22.4500
Smallest average lab result
15.0500
If proportion of labs removed from the total is less than 2/9, then
Cochran's Test =
92.0%
Critical value, 2.5% significance =
62.2%
Result =
Significant!
with maximum within lab variance for
Lab 11
If Cochran test is not significant, then proceed
Single Grubb's Test =
31.8%
Critical value, 2.5% significance =
38.8%
Result =
Not significant
highest average at
Lab 10
gives % decrease in standard deviation =
31.8%
lowest average at
Lab 5
gives % decrease in standard deviation =
0.3%
If Single Grubb's test is not significant, then proceed
Double Grubb's Test =
65.9%
Critical value, 2.5% significance =
52.1%
Result =
Significant!
Excluding the highest avg. and next highest avg
gives % decrease in standard deviation =
65.9%
Excluding the lowest avg. and next lowest avg
gives % decrease in standard deviation =
-1.8%
Excluding the highest avg. and lowest avg
gives % decrease in standard deviation =
33.3%