Michael Morton, Rana Tayyarah, and Jason Flora
Kunming, China
23 October 2018
Cigarette Variability (CVAR) Task
Force Study Designs, Statistical
Considerations, Initial Observations,
and Limitations
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❖ Cigarette Variability (CVAR) Task Force was formed in 2014
❖ Examining various smoke and filler constituents and select physical
properties
❖ Broken into three separate studies:
➢ Phase 1 – three samples over one week
➢ Phase 2 – four samples over a year
➢ Phase 3 – three samples, one sample in each of three years – preliminary data
are available
❖ The studies included nine products, but some had shipment difficulties
➢ 3R4F and, to a limited extent, 1R6F were also included
CVAR Task Force
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❖ Sample-to-sample variation is an estimate of how different one sample is
from another
➢ Variation among the “true” sample means
➢ Inferred from differences in the mean values associated with each sample
➢ With small numbers of samples (3 or 4 in our case), the sample-to-sample
standard deviation will not be well estimated, but we can see illustrative
examples of sample differences
❖ Power to detect differences
➢ 5 replicates per sample gives statistical power to detect sample
differences if sample-to-sample SD is ~1.3 times larger than rep-to-rep SD
Sample-to-sample variation
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❖ To avoid confusing laboratory drift with sample differences, samples
were put into cold storage (−23°C) so that all samples could be analyzed
at the same time
❖ Sample replicates were interleaved to provide additional protection
against lab drift affecting the sample-to-sample comparisons
❖ Filler analyses can give false statistically significant differences
➢ When tobacco filler replicates are subsamples from a single homogenized
sample sampling variability is lost and the criterion for a difference can
become too small
Statistical/Analytical Considerations
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❖ Examined the samples for statistically significant differences using the
analysis of variance
❖ Calculated percent differences: % Range = 100 * (max− min)/average
➢ This aids in determining if statistical differences are meaningfully large
❖ Compared sample-to-sample differences to 3R4F when split and treated
as separate samples
Statistical Analysis
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Results – Ventilation (%)
CVAR Task Force
2018 Congress, Kunming – 1810246
Product A B1 C B2 D E F Phase 1 Phase 2/1.21
1 40.2 38.1 38.9 38.9 38.5 38.8 37.8 3.4% 1.5%
2 59.2 59.3 56.8 59.2 58.4 55.8 56.3 5.9% 6.7%
3 0.4 0.3 0.4 0.3 0.2 0.6 0.4 0.1% 0.3%
4 26.5 20.1 24.9 21.4 24.5 22.6 27.6 8.4% 6.7%
6 23.4 22.7 23.3 - - - - 0.9% -
7 80.1 79.1 82.9 79.4 83.7 84.1 83.3 20.9% 21.3%
8 16.0 17.1 16.4 16.7 12.0 15.2 13.6 1.3% 4.6%
9 35.0 34.4 34.5 34.1 34.4 35.9 37.3 0.9% 4.1%
3R4F 31.1 - - 30.9 29.3 29.2 30.3 - 2.0%
5.9% 6.5%
Phase 1 Phase 2
Average Relative Ranges
Relative Ranges
Relative Ranges (%) = ((Max-Min)/(100-Avg of all 7 values) x 100. Relative range calculated as a percent of (100 – ventilation).
Note: Relative ranges are adjusted to account for 3 vs 4 data points by dividing Phase 2 ranges by 1.21
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❖ TNCO measured in each laboratory for each product
❖ Differences between labs were generally larger than those between
samples.
Results – Tar, Nicotine, and CO
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❖ TNCO measured in each laboratory for each product
❖ Differences between labs were generally larger than those between
samples.
Results – Tar, Nicotine, and CO
CVAR Task Force
2018 Congress, Kunming – 1810248
Product 4 ISO Tar (mg/cig) Phase 1
Lab A B1 C Lab Ave.
1 9.40 9.62 9.34 9.45
4 9.67 9.99 9.41 9.69
5 8.80 9.40 9.16 9.12
6 9.50 9.46 9.42 9.46
7 9.90 10.71 9.99 10.20
8 10.75 11.10 10.54 10.80
9 9.68 10.28 9.76 9.91
10 9.24 10.15 9.20 9.53
11 9.89 10.52 9.93 10.11
Ave. 9.65 10.14 9.64 9.81
% Sample Range 5.1%
%Lab Range 17.1%
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Nicotine in Filler (as-is)
Phase 1 – one week Phase 2 – one year
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❖ Filler Nicotine values showed larger differences over 1 year
compared to over 1 week (Percent Relative Ranges)
Filler Nic.
Product A B1 C B2 D E F Phase 1 Phase 2/1.21
1 13.8 14.1 13.9 13.7 14.3 14.8 15.1 2.1% 8.2%
2 16.6 16.8 16.6 17.3 16.1 15.4 15.1 1.0% 11.2%
3 16.4 15.8 15.6 15.0 14.9 15.4 14.8 4.9% 3.3%
4 15.1 15.4 15.6 15.6 15.5 15.5 15.0 3.1% 3.1%
6 16.4 16.5 16.4 16.7 16.7 15.9 15.9 1.0% 4.2%
7 16.8 17.6 17.2 17.0 17.4 17.9 17.4 4.7% 4.3%
8 18.5 18.4 18.1 18.2 18.8 18.7 18.1 2.1% 3.2%
9 15.5 15.3 15.9 16.0 17.5 16.9 17.2 3.7% 7.3%
3R4F 16.9 16.9 16.9 16.6 16.8 16.9 16.7 0.4% 1.4%
2.8% 5.6%Average Relative Ranges
Phase 1 Phase 2 Relative Ranges
1 week 1 year
CVAR Task Force
2018 Congress, Kunming – 181024
Relative Ranges (%) = ((Max-Min)/Avg of all 7 values) x 100 Note: Relative ranges are adjusted to account for 3 vs 4 data points by dividing Phase 2 ranges by 1.21
Filler Nicotine (mg/g) (as-is)
Phase 1 vs. Phase 2
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Nicotine in Filler and smoke – Phase 2
CVAR Task Force
2018 Congress, Kunming – 18102411
Nicotine in Filler (mg/g)
Product B2 D E F
1 13.65 14.28 14.84 15.07
2 17.31 16.12 15.44 15.11
3 15.01 14.86 15.39 14.77
4 15.61 15.53 15.45 15.04
6 16.72 16.68 15.89 15.88
7 17.02 17.40 17.92 17.35
8 18.23 18.82 18.74 18.10
9 16.00 17.45 16.86 17.15
3R4F 16.59 16.81 16.87 16.67
ISO Nicotine (mg/cig)
Product B2 D E F
1 0.769 0.761 0.814 0.811
2 0.303 0.313 0.313 0.295
3 0.843 0.825 0.837 0.848
4 0.740 0.723 0.749 0.717
6 1.161 1.146 1.207 1.166
7 0.103 0.066 0.056 0.060
8 0.794 0.895 0.775 0.817
9 0.653 0.682 0.658 0.644
3R4F 0.755 0.745 0.757 0.763
❖ There is a rough correspondence between nicotine in filler and nicotine in smoke
➢ Smoke generation has additional noise that weakens the correlation
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NNN in Filler (as-is)
CVAR Task Force
2018 Congress, Kunming – 181024
Phase 1 – one week Phase 2 – one year
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❖ Filler NNN values showed greater variability over 1 year
compared to over 1 week
Filler NNN
Product A B1 C B2 D E F Phase 1 Phase 2/1.21
1 727 726 717 791 1257 1248 1149 1.1% 40.7%
2 774 833 785 739 690 550 765 8.1% 24.2%
3 132 117 128 139 121 112 82 12.6% 40.3%
4 2308 2238 2283 2090 2416 2188 2247 3.1% 12.0%
6 1163 1155 1129 1091 1282 1132 1456 2.8% 25.1%
7 814 870 856 825 750 1059 949 6.3% 29.2%
8 93 105 108 108 107 98 78 15.1% 24.7%
9 571 675 751 671 431 306 383 33.4% 55.7%
3R4F 2817 2712 2742 2690 2767 2712 2754 3.8% 2.3%
10.3% 31.5%
Phase 1 Phase 2 Relative Ranges
Average Relative Ranges
1 week 1 year
CVAR Task Force
2018 Congress, Kunming – 181024
Relative Ranges (%) = ((Max-Min)/Avg of all 7 values) x 100 Note: Relative ranges are adjusted to account for 3 vs 4 data points by dividing Phase 2 ranges by 1.21
Filler NNN (ng/g) (as-is)
Phase 1 vs. Phase 2
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Smoke NNN Phase 2
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ISO NNN (ng/cig)
Product B2 D E F
1 45.0 65.4 60.0 50.7
2 14.5 14.9 13.2 14.6
3 6.00 6.36 7.28 5.88
4 91.6 93.8 89.9 88.6
6 68.5 66.0 71.5 71.8
7 7.88 4.80 5.12 4.84
8 4.48 6.16 4.20 3.84
9 27.0 17.8 18.2 19.3
3R4F 113 110 124 106
CI NNN (ng/cig)
Product B2 D E F
1 105 154 159 155
2 61 61 46 53
3 14.1 17.5 13.0 9.1
4 216 219 209 213
6 151 164 142 175
7 82 65 68 71
8 10.7 10.7 9.5 9.3
9 72 55 46 43
3R4F 267 277 268 250
Filler NNN (ng/g)
Product B2 D E F
1 791 1257 1248 1149
2 739 690 550 765
3 139 121 112 82
4 2090 2416 2188 2247
6 1091 1282 1132 1456
7 825 750 1059 949
8 108 107 98 78
9 671 431 306 383
3R4F 2690 2767 2712 2754
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❖ Smoke B[a]P values showed similar variability over 1 year
compared to 1 week
CI B[a]P
Product A B1 C B2 D E F Phase 1 Phase 2/1.21
1 16.0 16.3 16.4 16.8 17.4 16.8 17.2 2.1% 3.2%
2 6.6 6.6 6.5 6.8 6.8 6.7 6.9 2.8% 3.0%
3 13.1 13.4 13.4 13.1 14.0 13.7 13.7 2.7% 6.0%
4 15.7 15.8 16.0 15.2 14.9 15.3 15.0 2.1% 1.7%
6 10.8 11.0 11.0 11.7 11.5 11.3 11.9 1.8% 4.7%
7 6.5 6.5 6.5 7.0 7.0 6.8 7.0 0.4% 2.2%
8 12.6 13.1 13.0 12.1 12.6 12.4 12.3 3.8% 3.5%
9 10.0 10.3 10.4 10.3 10.3 10.0 10.7 3.1% 6.1%
3R4F 15.0 15.1 15.3 16.2 16.2 15.7 15.3 2.3% 5.2%
2.4% 3.8%
Phase 1 Phase 2 Relative Ranges
Average Relative Ranges
1 week 1 year
Relative Ranges (%) = ((Max-Min)/Avg of all 7 values) x 100 Note: Relative ranges are adjusted to account for 3 vs 4 data points by dividing Phase 2 ranges by 1.21
CVAR Task Force
2018 Congress, Kunming – 181024
CI Smoke B[a]P (ng/cig)
Phase 1 vs. Phase 2
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❖ With a small number of samples per product, variability will not be quantitatively
well estimated, but illustrative examples of differences are possible
❖ Samples were all put into cold storage so that all could be analyzed at the same
time to avoid confusing laboratory shifts with sample differences
❖ In the short-term, generally filler differences and smoke yield differences are
small
❖ In the longer term, tobacco filler and related smoke yield differences are often
larger
❖ Smoke yields of tobacco related constituents broadly follow the filler
concentrations
❖ Combustion related analytes tend to differ less than tobacco related analytes
Summary
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