The computations and analyses were carried out in STATA by computing person-years for each woman from their dates of entry and exit by each year, which was added to their total person-years for that year.
Furthermore, collecting exposures as event based counts prohibits us from computing person-time more precisely (in h/min player), and this limits our understanding particularly with respect to game-related injury incidence.
Winsteps software (Linacre and Wright 2000) was used to compute person measures for the BARSTL survey results for all participants in this study, and to transform the original logit range to a more comparable, but still linear, scale ranging from 0 to 100.
We computed person years of exposure as the sum of follow-up time among decedents and survivors.
42 We computed person time from baseline to the date of death from any cause or the date of the third active follow-up visit, whichever came first.
In both cohorts, we computed person years of follow-up to the date of diagnosis of pancreatic cancer, death from any cause, or to the end of the study period (June 1 , 1998 for women, and February 1 , 1998for men) whichever occurred first.
We used the NIOSH personal computer life table analysis system (Steenland et al. 1998) to compute person-years at risk (PYAR), expected numbers of deaths, and standardized mortality ratios (SMRs) based on U.S. and appropriate state and county rates.
For each cell of the cross-classification, we computed person-year weighted means for the cross-classification variables.
We computed person-years from baseline to the date of the first CVD event or the date of the third follow-up visit.
We computed person-years for the LC cohort as the difference of the date of interview to the date of death, loss to follow-up, or end of the study period (31 December 1996).
