[Study of logistic curve fitting for primary liver cancer death rate in Chengdu]

Logistic curve was used for fitting primary liver cancer (PLC) age-specific death rate in Chengdu. The results showed that the age-specific death rate from 1981 to 1986 in Chengdu (population about 4,000,000) was satisfactorily fitted by logistic curve in male, female and total (P less than 0.01). The R2s were 0.9885, 0.9912 and 0.9974, respectively. Velocity analysis of death rate showed that the increasing peak was in the group of age 40-60 for male and 50-65 for female. Male's velocity and slope of death rate were higher and steeper than female's. These results are consistent with the feature of logistic curve and parameters obtained from logistic curve fitting in this study. The age-specific death rate by sex for every year from 1981 to 1986 was fitted very well (P less than 0.01). R2s for male and female were 0.9415 +/- 0.044 and 0.9056 +/- 0.048, respectively.