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Summary: 



1. Nicotine Levgjg; 



When one looks at average nicotine levels over the years 

 1982-1991, one finds that the levels are trending upward. This 

 is true both within each of the three categories (high tar, low 

 tar, and ultra low tar), and averaged across all brands. 



Within each of the three categories based on tar level, the 

 upward trend in nicotine levels is statistically significant. 

 This does not appear to be an artifact of a particular method of 

 statistical analysis. The upward trends remain significant when 

 any of several analyses are used. 



When one looks at the average over all brands, the trend is 

 marginally statistically significant. Depending on the method of 

 analysis, the trend is significant with a p-value between .07 and 

 .024. (The analysis with the higher p-value is a weighted 

 regression which puts substantially more weight on the later 

 years. As the graphs show, nicotine levels are somewhat flatter 

 in the years 1987-91 than in the whole time period 1982-91. This 

 may account for the diminished statistical significance.) 



2. Tar Levels: 



As was done with nicotine, one can also look at trend in 

 average tar levels over time. If one looks at average tar levels 

 within the three categories of high, low and ultra low tar 

 cigarettes, one does not find any statistically significant trend 

 upward or downward over the time period 1982-91. Since this 

 analysis is stratifying on tar levels, it may be an artifact that 

 no trend is found. 



A more relevant analysis for tar levels over the time period 

 1982-91 is the tar level averaged over all varieties of 

 cigarettes. This average tar level has been trending downward to 

 a statistically significant extent. (The p-value for a downward 

 trend is between .0248 and .0425, depending on the method of 

 analysis chosen.) 



An apparent explanation of the downward trend in average tar 

 levels is increasing market share of low tar and ultra low tar 

 cigarettes. (Ultra low tar cigarettes have increased from 8.1% 



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