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Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 1 of 42
CORESTA Monitoring and Maintenance of Physical Test Methods Sub - Group
2009 Interlaboratory Proficiency Test
Issued by:
Graham Errington
R & D Centre
British American Tobacco
Regents Park Road
Millbrook
Southampton
United Kingdom
SO15 8TL
Phone: 02380 793540
e-mail: [email protected]
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 2 of 42
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 3 of 42
PARTICIPATING LABORATORIES British American Tobacco (Germany) GmbH, Weistrasse 26, 95448 Bayreuth, Germany
British American Tobacco, Denmark
Cerulean, Rockingham Drive, Linford Wood East, Milton Keynes, MK14 6LY, UK
Hauni
Imperial Tobacco - HH
Imperial Tobacco - LA
Product Research Division, Japan Tobacco Inc., JT Sumida Building, 17-7, Yokogawa 1-chome, Sumida-ku,
Tokyo 130-8603, Japan
JT International Germany GmbH, Zentrale Warenaufnahme, R & D Building/GQA-Laboratories,
Diedenhofener Str. 20, D-54294 Trier, Germany
Rhodia Acetow GmbH, Engesserstr. 8, D-79123 Freiburg, Germany
SODIM SA, 4 rue André Dessaux, 45404 Fleury les Aubrais cedex, France
ST Poland, 32-400 Myslenice, Jawornik 360, Poland
Papierfabrik Wattens GmbH & Co KG, Ludwig-Lassl-Strasse 15, A-6112 Wattens, Austria
Zhengzhou Tobacco Research Institute of CNTC, No. 2 Fengyang St., Zhengzhou New & High-Tech Industries, Development Zone, Henan 450001, China
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 4 of 42
2009 CORESTA MMPTM SUB – GROUP INTERLABORATORY PROFICIENCY TEST
Introduction The purpose of an interlaboratory proficiency testing scheme
1 is to provide participating laboratories
with an objective means of assessing and demonstrating the reliability of the data they are producing, and is an important component of any laboratory quality assurance scheme. The importance of proficiency testing is recognised in ISO/IEC Guide 17025
2 where “participation in interlaboratory
comparison or proficiency testing programmes” is listed as an important component of quality assurance results.
Outline of Test Protocol Five filter types and five cigarette brands were selected to cover the range of interest for Individual Weight, Circumference, Pressure Drop and Ventilation.
The samples used in the study are presented in Table 1.
Table 1.
SAMPLE TYPE
SAMPLE ID VARIANT Pressure Drop
Type
Monoaceate
Filter
F1 Semi - Slim
F2 Slim
F3 King Size/ Regular High
F4 King Size/ Regular Low
F5 King Size/ Regular Medium
Cigarette
C1 King Size/ Regular
C2 King Size/ Regular
C3 Slim
C4 Super Slim
C5 Super Slim
Participating laboratories were instructed to measure a sub – group of 10 specimens under their normal operating conditions, repeated 3 times for each sample. Mean values of each replicate were reported in an Excel spreadsheet supplied with the protocol.
After completion, the spreadsheets were returned to the author for data analysis.
Data Analysis Statistical analysis was carried out using Microsoft Excel and MINITAB v15. All graphs were produced with MINITAB v15.
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 5 of 42
Summary statistics were calculated for each sample, followed by individual value plots by laboratory, to identify potential outliers.
Precision Statistics
Following identification and removal of outliers, Reproducibility, R, and repeatability, r, were calculated for each sample and tabulated at the beginning of each section.
Mandel Plots
h statistics for between laboratory consistency, and k statistics for within laboratory consistency were calculated and plotted according to ISO 5725 – 2
3, for each product characteristic
Repeatability Variation (Cochran’s Test)
Cochran’s test4 was used to evaluate the within – laboratory performance of each laboratory
where smax is the highest standard deviation in a set of p laboratories. The following criteria were used to asses each laboratory:
If the test statistic, c, is:
- ≤ 5% critical value Accept
- > 5% critical value ‹ 10% critical value Straggler
- > 10% critical value Outlier
Z - scores
After removal of outliers, robust estimates of means of all laboratories were used as the reference for computing z – scores
Z – scores are plotted in ascending order. Laboratory performance is indicated using the following criteria:
|z| < 1 = good
1< |z| < 2 = satisfactory
2< |z| < 3 = questionable
|z| > 3 = highly questionable
Results are presented separately for Filters and cigarettes.
p
i
is
sc
1
2
2
max
outliers for adjusted deviation standard overall
value mean Total
value mean Single
-
s
X
x
s
XxZ
)(
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 6 of 42
FILTER DATA ANALYSIS
Table 2. Filter Summary Statistics
Instrument Manufacturer/ Type Codes for Individual Value Plots
Instrument Manufacturer/Type Code
Borgwaldt 1
Cerulean 2
Sodiline 3
Sodimat 4
Sodimax 5
Sodimax CCD 6
VariableSample
IDN N* Mean StDev CoefVar Minimum Median
Maximu
mRange
F2 42 0 461.45 3.660 0.79 452.50 462.73 466.00 13.500
F1 41 1 510.45 3.770 0.74 501.30 512.00 518.00 16.700
F4 42 0 798.88 6.490 0.81 784.60 800.00 810.50 25.900
F5 42 0 894.37 6.400 0.72 878.40 895.23 903.00 24.600
F3 42 0 1044.20 8.000 0.77 1025.30 1047.00 1055.80 30.500
F2 42 0 18.00 0.028 0.16 17.93 18.01 18.04 0.117
F1 41 1 21.18 0.034 0.16 21.10 21.19 21.24 0.143
F5 42 0 24.47 0.037 0.15 24.39 24.47 24.55 0.165
F4 42 0 24.43 0.038 0.15 24.34 24.45 24.49 0.146
F3 42 0 24.43 0.049 0.20 24.23 24.45 24.49 0.260
F4 39 3 243.54 6.070 2.49 222.80 244.00 253.00 30.200
F1 38 4 396.98 12.760 3.21 351.90 396.60 414.30 62.400
F2 36 6 412.96 13.300 3.22 370.90 416.00 429.00 58.100
F5 39 3 538.44 25.480 4.73 432.40 544.70 565.00 132.600
F3 39 3 779.62 47.290 6.07 598.60 791.40 818.00 219.400
Individual Wt Mean mg
Circum Mean mm
PD (fully encapsulated)
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 7 of 42
Filter Rod Individual Weights
Laboratory N did not measure weights on any filter samples.
Precision Statistics Individual weights data were screened for outliers and precision statistics calculated for each filter sample.
Table 3. Filter Rod Individual Weights Precision Statistics.
Individual value plots for each sample are shown in Fig.1. Individual data points are represented by solid symbols, and laboratory means by open circles.
Mandel Plots
The h statistic Mandel Plots (Fig.2) show that no laboratory is significantly different.
There are no apparent exceptional values in the k – statistic plots in Fig. 3.
Repeatability Variation
Cochran’s test did not identify any exceptional variances.
Z – scores (Fig.4)
Results for Laboratory C are questionable for all filters.
Filter Type Sample ID Mean sr sR r R CoV
SemiSlim F1 510.5 1.48 3.77 4.14 10.56 0.74
Slim F2 461.5 1.27 3.66 3.56 10.25 0.79
KS F3 1044.2 2.92 8.00 8.18 22.40 0.77
KS F4 798.9 3.36 6.49 9.41 18.17 0.81
KS F5 894.4 2.54 6.40 7.11 17.92 0.72
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 8 of 42
Figure 1. Filter Rod Individual Weights – Individual Value Plots
Individual Values represented by solid symbols, mean values represented by open circles.
NJMIFEAHGPKDCBL
520
510
500
Indiv
idual W
t M
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NJMIFEAHGPKDCBL
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NJMIFEAHGPKDCBL
1050
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NJMIFEAHGPKDCBL
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NJMIFEAHGPKDCBL
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Inst_Code
Sample_ID = F1 Sample_ID = F2
Sample_ID = F3 Sample_ID = F4
Sample_ID = F5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 9 of 42
Figure 2. Filter Rod Individual Weights – h statistic Mandel Plots
Sample F5F4F3F2F1
2
1
0
-1
-2
h
kcrit
kcrit
J
K
L
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P
A
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C ode
Lab
Lab C ode PMLKJIHGFEDCBA
2
1
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-1
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h
hcrit
hcritF 1
F2
F3
F4
F5
Sample
Individual Weight h statistics - Labs within Samples
Individual Weight h statistics - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 10 of 42
Figure 3. Filter Rod Individual Weights – k statistic Mandel Plots
Sample F5F4F3F2F1
2.0
1.5
1.0
0.5
0.0
k
kcrit
J
K
L
M
P
A
B
C
D
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G
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C ode
Lab
Lab C ode PMLKJIHGFEDCBA
2.0
1.5
1.0
0.5
0.0
k
kcritF 1
F2
F3
F4
F5
Sample
Individual Weight k statistics - Labs within Samples
Individual Weight k Statistics - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 11 of 42
Figure 4. Filter Rod Individual Weights – z -Score Plots
CKBMFAJHEDLPGI
3
2
1
0
CBKMIDFPALHGJE
3
2
1
0
CBKMDAIFPJGLHE
3
2
1
0
CKBDIMFJEAHGLP
3
2
1
0
CKMBADPFGIHLEJ
3
2
1
0
F1 F2
F3 F4
F5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 12 of 42
Filter Circumference
Table 4. Filter Circumference Precision Statistics.
Results for Lab N excluded. One outlier removed sample F3, laboratory J.
Individual value plots for each sample are shown in Fig.5. Individual data points are represented by solid symbols, and laboratory means by open circles.
Mandel Plots
Mandel plots do not show any laboratories beyond critical values (Note Laboratory N was not included in any of the filter analysis, and one measurement removed from sample F3, laboratory J).
Repeatability Variation
Cochran’s test did not show any labs as outliers (one measurement removed form laboratory J).
Z – scores
Results for Laboratory C (Fig.8) are questionable for Filters F1 and F2.
Results for Laboratory B, Filters F2 and F4 are questionable.
Laboratories with missing data points did not, or were unable to, measure the samples.
Filter Type Sample ID Mean sr sR r R CoV
SemiSlim F1 21.180 0.015 0.034 0.041 0.096 0.16
Slim F2 18.000 0.009 0.028 0.024 0.078 0.16
KS F3 24.440 0.016 0.037 0.044 0.104 0.15
KS F4 24.430 0.014 0.038 0.039 0.106 0.15
KS F5 24.470 0.019 0.037 0.052 0.102 0.15
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 13 of 42
Figure 5. Filter Rod Circumference – Individual Value Plots
JMIFEAHGPKDCBL
21.20
21.15
21.10
Circum
Mean m
m
1
2
3
4
5
Inst_Code
JMIFEAHGPKDCBL
18.05
18.00
17.95
Circum
Mean m
m
1
2
3
4
5
Inst_Code
JMIFEAHGPKDCBL
24.45
24.40
24.35
Circum
Mean m
m
1
2
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4
5
Inst_Code
JMIFEAHGPKDCBL
24.45
24.40
24.35
Circum
Mean m
m
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Inst_Code
JMIFEAHGPKDCBL
24.56
24.48
24.40
Circum
Mean m
m
1
2
3
4
5
Inst_Code
Sample_ID = F1 Sample_ID = F2
Sample_ID = F3 Sample_ID = F4
Sample_ID = F5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 14 of 42
Figure 6. Filter Rod Circumference: h – statistic Mandel Plots
Sample F5F4F3F2F1
2
1
0
-1
-2
h
hcrit
hcrit
J
K
L
M
P
A
B
C
D
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Lab
Lab C ode PMLKJIHGFEDCBA
2
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h
hcrit
hcritF 1
F2
F3
F4
F5
Sample
Filter Circumference h Statistics - Labs within Samples
Filter Circumference h Statistics - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 15 of 42
Figure 7. Filter Rod Circumference: k – statistic Mandel Plots
Sample F5F4F3F2F1
2.0
1.5
1.0
0.5
0.0
k
kcrit
J
K
L
M
P
A
B
C
D
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F
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C ode
Lab
Lab C ode PMLKJIHGFEDCBA
2.0
1.5
1.0
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k
kcritF 1
F2
F3
F4
F5
Sample
Filter Circumference k - Statistics - Labs within samples
Filter Circumference k - Statistics - Samples within labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 16 of 42
Figure 8. Filter Rod Circumference z -score Plots
CBAKDPMHEFLGIJ
2
1
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Z_F1
BCDFAMKPLHJIGE
2
1
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Z_F2
CBKHGMEADJPILF
2
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Z_F3
BCKAPFMDGHILJE
2
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Z_F4
CMAKGLBFPIHDJE
2
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LAB ID_F5
Z_F5
F1 F2
F3 F4
F5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 17 of 42
FILTER ROD PRESSURE DROP
Table 5. Filter Rod Pressure Drop Precision Statistics
Laboratories N and B not included.
Filter Type Sample ID Mean sr sR r R CoV
SemiSlim F1 400.030 2.603 6.770 7.288 18.956 1.69
Slim F2 416.170 2.297 7.720 6.432 21.616 1.86
KS F3 792.420 5.513 12.880 15.436 36.064 1.63
KS F4 244.620 2.519 3.960 7.053 11.088 1.62
KS F5 545.230 3.266 6.950 9.145 19.460 1.27
Individual value plots for each sample are shown in Fig.9. Individual data points are represented by solid symbols, and laboratory means by open circles.
Mandel Plots
The h statistic Mandel Plots (Fig.10) show that Laboratory B is significantly different from the grand mean for all filters.
The k statistic plot (Fig.11) shows that Laboratory B’s within – laboratory variation is significantly different for all samples
Repeatability Variation
Cochran’s test identifies the results for all filters for laboratory B as outliers.
Z – scores
Results for all filters for Laboratory B were identified as outliers
Laboratories with missing data points did not, or were unable to, measure the samples.
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 18 of 42
Figure 9. Filter Rod Pressure Drop – Individual Value Plots
PMLKJIHGFEDCBA
400
375
350
PD
(fu
lly e
ncapsula
ted)
Mean m
m
J
K
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PMLKJIHGFEDCBA
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PMLKJIHGFEDCBA
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(fu
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m
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PMLKJIHGFEDCBA
550
500
450PD
(fu
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ncapsula
ted)
Mean m
m
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Lab_Code
Sample_ID = F1 Sample_ID = F2
Sample_ID = F3 Sample_ID = F4
Sample_ID = F5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 19 of 42
Figure 10. Filter Rod Pressure Drop: h - statistic Mandel Plots
F5F4F3F2F1
2
0
-2
-4
h
hcrit
hcrit
J
K
L
M
P
A
B
C
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C ode
Lab
PMLKJIHGFEDCBA
2
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h
hcrit
hcrit
F 1
F2
F3
F4
F5
Sample
Filter PD h Statistics - Labs within Samples
Filter PD h Statistics -Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 20 of 42
Figure 11. Filter Rod Pressure Drop: k - statistic Mandel Plots
F5F4F3F2F1
2.4
1.8
1.2
0.6
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k
kcrit
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PMLKJIHGFEDCBA
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kcrit
F 1
F2
F3
F4
F5
Sample
Filter PD k Statistics - Labs within Samples
Filter PD k Statistics - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 21 of 42
Filter Rod Pressure Drop – Repeatability Variation
Laboratory G did not submit data. All samples from Laboratory B were outliers.
Figure 12. Filter Rod Pressure Drop: z – score Plots
GBPAMICDHFLJEK
3
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Z_Score
LGBICAMPDKHEFJ
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GBAIMPDKFLJHEC
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GBACILHMJEFPDK
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GBAIMPEKFCDHJL
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F1 F2
F3 F4
F5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 22 of 42
CIGARETTE DATA ANALYSIS
Laboratory P did not measure cigarettes. Laboratory N only measured circumference, but the values are not included in the analysis because they are wildly different from the rest of the laboratories. Laboratory I did not report PDo or Ventilation results.
Table 6. Cigarette Summary Statistics
Instrument Manufacturer/ Type Codes for Individual Value Plots
Instrument Manufacturer/Type Code
Borgwaldt 1
Cerulean 2
Sodiline 3
Sodimat 4
Sodimax 5
Variable Sample_ID N N* Mean StDev CoefVar Minimum Median Maximum
C1 39 0 954.86 13.410 1.4 921.00 954.00 993.90
C2 39 0 958.76 12.270 1.3 936.00 959.00 986.00
C3 39 0 716.26 10.620 1.5 688.00 717.00 741.60
C4 39 0 664.49 14.390 2.2 636.00 666.00 695.50
C5 39 0 657.69 12.580 1.9 633.00 661.00 680.70
C1 39 0 24.98 0.488 2.0 24.80 24.90 27.92
C2 39 0 25.01 0.491 2.0 24.84 24.94 27.97
C3 39 0 21.46 0.075 0.4 21.24 21.45 21.71
C4 39 0 18.02 0.027 0.2 17.97 18.01 18.08
C5 39 0 18.05 0.324 1.8 17.93 17.99 19.97
C1 36 3 118.71 6.200 5.2 100.10 119.75 127.80
C2 36 3 108.61 4.270 3.9 95.90 108.95 117.50
C3 36 3 120.00 3.130 2.6 115.00 119.50 126.80
C4 36 3 182.98 9.100 5.0 175.00 180.05 212.40
C5 36 3 98.32 31.250 31.8 85.00 88.75 204.10
C1 36 3 20.86 6.580 31.5 17.43 19.00 42.70
C2 36 3 29.53 5.780 19.6 26.53 27.84 48.70
C3 36 3 42.58 2.844 6.7 40.60 41.80 52.30
C4 36 3 46.10 4.570 9.9 41.85 45.05 61.20
C5 36 3 81.17 0.836 1.0 78.80 81.40 82.60
Individual Wt Mean mg
Circum Mean mm
PD open Mean mmWG
Vent % Mean
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 23 of 42
CIGARETTE INDIVIDUAL WEIGHTS
Table 7. Cigarette Individual Weights – Precision Statistics
Individual value plots for each sample are shown in Fig.13. Individual data points are represented by open circles, and laboratory means by solid circles.
Mandel Plots
The h statistic Mandel Plots (Fig.14) do not show any laboratories significantly different from the reference value.
The k statistic plot (Fig.15) does not suggest exceptional variation for any single laboratory.
Repeatability Variation
Cochran’s test shows repeatability variation is acceptable for all laboratories.
Z – scores
Results for Laboratory D (Fig.16), cigarette 1 and 3 are questionable. Results for Laboratory C are questionable.
There are no questionable results for cigarettes 2, 4 and 5.
Laboratories with missing data points did not, or were unable to, measure the samples.
Cigarette Type Sample ID Mean sr sR r R CoV
SuperSlim C5 657.7 4.53 12.58 12.68 35.22 1.9
SuperSlim C4 664.5 6.57 14.39 18.40 40.29 2.2
Slim C3 715.7 4.38 6.53 12.26 18.28 0.9
KS C1 955.5 7.09 9.86 19.85 27.61 1.0
KS C2 958.8 0.57 12.27 1.59 34.36 1.3
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 24 of 42
Figure 13. Cigarette Individual Weights – Individual Value Plot
JMIFEAHGKDCBL
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Sample_ID = C1 Sample_ID = C2
Sample_ID = C3 Sample_ID = C4
Sample_ID = C5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 25 of 42
Figure 14. Cigarette Individual Weights: h – statistic Mandel Plots
C 5C 4C 3C 2C 1
2
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Sample
Individual Weights h statistics - Labs within Samples
Individual Weights h statistics - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 26 of 42
Figure 15. Cigarette Individual Weights: k – statistic Mandel Plots
C 5C 4C 3C 2C 1
2.0
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C 3
C 4
C 5
Sample
Individual Weight k statistics - Labs within Samples
Individual Weight k statistics- Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 27 of 42
Cigarette Individual Weights; Repeatability Variation
Cochran’s test did not show any laboratories with exceptional variation.
Figure 16. Cigarette Individual Weights: z -score Plots
DCBMKJLIEHFGA
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Questionable
DBCKFMLGHEJIA
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Questionable
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DCBLEKMIJAGHF
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Questionable
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DCKBMIJLFGHEA
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Questionable
Sample C1 Sample C2
Sample C3 Sample C4
Sample C5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 28 of 42
CIGARETTE CIRCUMFERENCE
Table 8. Cigarette Circumference Precision Statistics
Individual value plots for each sample are shown in Fig. 17. Individual data points are represented by open circles, and laboratory means by solid circles.
Mandel Plots
The h statistic Mandel Plots (Fig.18) shows that Laboratory L is significantly different for cigarette C5
The k statistic plot (Fig.19) identifies Laboratory A as significantly different for cigarette C3, and Laboratory L for cigarette C5.
Repeatability Variation
Cochran’s test shows Laboratory A cigarette C3, and Laboratory L, cigarette C5 as outliers, and Laboratory A cigarette C4 as straggler.
Z – scores
Results for Laboratory L, cigarette C5 (Fig.20) are highly questionable, results for Laboratory A cigarettes C1 and C2, are questionabel.
Laboratories with missing data points did not, or were unable to, measure the samples.
Cigarette Type Sample ID Mean sr sR r R CoV
SuperSlim C5 17.99 0.020 0.026 0.057 0.072 0.14
SuperSlim C4 18.02 0.024 0.027 0.066 0.076 0.15
Slim C3 21.45 0.022 0.046 0.063 0.129 0.21
KS C1 24.90 0.037 0.058 0.104 0.162 0.23
KS C2 24.92 0.040 0.051 1.588 0.143 0.21
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 29 of 42
Figure 17. Cigarette Circumference Individual Value Plots
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Sample_ID = C1 Sample_ID = C2
Sample_ID = C3 Sample_ID = C4
Sample_ID = C5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 30 of 42
Figure 18. Cigarette Circumference: h – statistics Mandel Plots
Sample C 5C 4C 3C 2C 1
4
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Sample
Cigarette Circumference h Statistics - Labs within Samples
Cigarette Circumference h Statistics - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 31 of 42
Figure 19. Cigarette Circumference: k – statistics Mandel Plots
Lab C ode MLKJIHGFEDCBA
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Cigarette Circumference k - Statistics - Samples within Labs
Cigarette Circumference k -Statistics - Labs within Samples
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 32 of 42
Cigarette Circumference – Repeatability Variation
Laboratory A cigarette C3 and Laboratory L, cigarette C3 as outliers, and Laboratory A cigarette C4 as a straggler.
Figure 20. Cigarette Circumference: z -score Plots
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Plot of Z Score Cigarette C1 Plot of Z Score Cigarette C2
Plot of Z Score Cigarette C3 Plot of Z Score Cigarette C4
Plot of Z Score Cigarette C5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 33 of 42
CIGARETTE PRESSURE DROP (OPEN)
Table 9. Cigarette Pressure Drop (Open) – Precision Statistics
The Individual values plots for cigarette pressure drop identified Laboratory C as different enough to distort the scale on the graphs. The plots were redrawn without these values (Fig.21).
Mandel Plots
The h statistic Mandel Plots (Fig.22) shows that Laboratory C is significantly different from the reference value, for all cigarettes except C3.
The k statistic plot (Fig.23) does not suggest exceptional variation for any single laboratory.
Repeatability Variation
Cochran’s test did not identify any outliers.
Z – scores
Laboratory C gave questionable results for cigarettes C1, C2, C4 and C5 (Fig.24). There were no questionable results for cigarette C3
Laboratories with missing data points did not, or were unable to, measure the samples.
Cigarette Type Sample ID Mean sr sR r R CoV
SuperSlim C5 88.8 1.40 2.95 3.92 8.26 3.32
SuperSlim C4 180.6 3.35 4.35 9.38 12.18 2.41
Slim C3 120.0 1.57 3.13 4.40 8.76 2.61
KS C1 120.3 1.48 3.18 4.14 8.90 2.64
KS C2 109.4 1.19 2.23 3.33 6.24 2.04
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 34 of 42
Figure 21. Cigarette Pressure Drop: Individual Value Plots
Labs N. I. P did not measure cig Pressure Drop, Lab C results removed from individual value plots.
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Sample_ID = C1 Sample_ID = C2
Sample_ID = C3 Sample_ID = C4
Sample_ID = C5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 35 of 42
Figure 22. Cigarette Pressure Drop: h – statistics Mandel Plots
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Sample
Pressure Drop (open) h statistics - Labs within Samples
Pressure Drop (open) h statistics - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 36 of 42
Figure 23. Cigarette Pressure Drop: k – statistics Mandel Plots
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Pressure Drop (open) k statistics - Samples within Labs
Pressure Drop (open) k statistics - Labs within Samples
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 37 of 42
Cigarette Pressure Drop (open) – Repeatability Variation: Cochran’s Test
Cochran’s test identified Labs B and C as stragglers for sample C5. There were no unusual results for the other 4 samples
Figure 24. Cigarette Pressure Drop: z - score Plots
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Cig C1 Cig C2
Cig C3 Cig C4
Cig C5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 38 of 42
CIGARETTE VENTILATION
Table 10. Cigarette Ventilation: Precision Statistics
The Individual values plots for cigarette pressure drop identified Laboratory C as different enough to distort the scale on the graphs. The plots were redrawn without these values (Fig.25).
Mandel Plots
Laboratory C was excluded from the Mandel plotsbecause of distortion of the graphs.
The h statistic Mandel Plots (Fig.26) shows that Laboratory B is significantly different from the reference value, for cigarettes C4 and C5. Laboratories A and B, in general, show a greater deviation form the reference values
The k statistic plot (Fig.27) does not shows any exceptional variation
Repeatability Variation
Cochran’s test did not suggest any exceptional variation.
Z – scores
Results for Laboratory C (Fig.28) are highly questionable for C1, C2 , C3 and C4, and questionable for C5.
Results for Laboratory A , cigarette C2 are questionable.
Results for Laboratory B cigarette C4 are questionable.
Laboratories with missing data points did not, or were unable to, measure the samples, or had extreme values which distorted the plots.
Cigarette Type Sample ID Mean sr sR r R CoV
SuperSlim C5 81.4 0.394 0.498 1.103 1.394 0.61
SuperSlim C4 44.9 0.643 0.938 1.800 2.626 2.09
Slim C3 41.8 0.334 0.428 0.935 1.198 1.02
KS C2 27.8 0.567 0.861 1.588 2.411 3.09
KS C1 18.9 0.399 0.573 1.117 1.604 3.03
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 39 of 42
Figure 25. Cigarette Ventilation: Individual Value Plots
Laboratory C excluded from graphs because of wildly different results.
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Sample_ID = C1 Sample_ID = C2
Sample_ID = C3 Sample_ID = C4
Sample_ID = C5
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 40 of 42
Figure 26. Cigarette Ventilation: h – statistics Mandel Plots
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Ventilation h Statistic - Labs within Samples
Ventilation h Statistic - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 41 of 42
Figure 27. Cigarette Ventilation: k – statistics Mandel Plots
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Ventilation k Statistic - Labs within Samples
Ventilation k Statistic - Samples within Labs
Coresta Sub Group
Monitoring and Maintenance of Physical Test Methods
Interlaboratory Proficiency Test 2009
Page 42 of 42
Cigarette Ventilation: Repeatability Variation
All results were acceptable using Cochran’s test.
Figure 28. Cigarette Ventilation: z –score Plots
1 ISO/IEC Guide 43 – 1: 1997: Proficiency testing by interlaboratory comparisons – Part 1:
Development and operation of proficiency testing schemes
2 ISO/IEC 17025: 2005 General requirements for establishing the competence of calibration and
testing laboratories
3 ISO 5725 – 2 Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method
4 ibid.
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Plot of C1 Z Scores Plot of C2 Z Scores
Plot of C3 Z Scores Plot of C4 Z Scores
Plot of C5 Z Scores