Following Peto's advice(ref. 1, p.

Following Peto's advice(ref. 1, p. 402)the continuity correction was not applied.Not making this correction resulted in lowering the p-value and in increasing the risk of a false positive.When the asymptotic p-value was at least marginally statistically significant(p 0.10)and when the total number of tumor bearing animals in all treatment groups was 8 or less, the "exact" age-adjusted Cochran-Armitage trend was computed also and it was preferred.The resulting p-value was the "exact" probability that a trend was greater than or equal to the one observed.For computer technical reasons, experimental periods in tables are expressed in lunar months(28 days or 4 weeks).Computer print-outs refer mostly to a carcinogenicity study of 24 calendar months duration as originally planned.The study was extended to 25 calendar months or approximately 28 lunar months(111 weeks).- report archive(Building 070)- specimen archive(Building 162)- technical maintenance unit(Building 260).Test for positive dose related trend- Cumulative mortality rate per lunar monthAfter 24 calendar months(26 lunar months), mortality in the control group was 42% in males and 40% in females respectively.Termination of the study was decided after approximately 28 lunar months or 109-111 weeks(=25 calendar months)when mortality was about 50% in the control group and the low dose group of both males and females.When mortality rate(dead or sacrificed animals)in the dosed groups was compared with that of the control group(see pages R 1.3 - R 1.5), the following was noted:Trend analysis did not reveal a positive dose related trend in mortality rate Intergroup comparison, using the Chi-square test, showed a significantly(p