Determining When Annual Crude Mortality Rate Most Recently Began Increasing in North Dakota Counties, I: Backward-Stepping Little Jiffy

Paul R. Yarnold

Optimal Data Analysis, LLC

Recent research tested the hypothesis that the annual crude mortality rate (ACMR) was higher after versus before 1998 in counties of North Dakota, due to increased exposure of the population to environmental toxins and hazards beginning approximately at that time. This hypothesis was confirmed with experimentwise p<0.05 for 16 counties. This article investigates the ACMR time series for each of these counties using a backward-stepping little jiffy UniODA analysis to ascertain precisely when ACMR began to increase. As hypothesized the ACMR began increasing in Bowman and Kidder counties precisely in 1998. Consistent with the a priori hypothesis the initial (and presently sustained) increase in ACMR occurred in McLean county in 1997, and in Foster county in 1996. Significant sustained increases in ACMR initially began in Stark county in 1993, and in Burleigh county in 1988. The UniODA models identified hypothesized, recent, powerful, sustained, statistically significant increases in ACMR.

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