Vital Statistics are easily influenced by random variation and single-year rates can fluctuate from year to year. A multiple year rate such as a 5- to 10-year average of single-year rates would be more accurate in formulating conclusions on vital events. For example, the infant death rate for Kansas has ranged from 8.7 to 7.4 infant deaths per 1,000 live births in 1993 to 1997, respectively. The 1993-1997 5-year infant death rate for Kansas was 7.8 infant deaths per 1,000 live births. The 5-year rate smooths some of the variation in single-year rates and would be a more reliable indicator of infant death rates in Kansas.

Rates based on a small or large number of events in a sparsely populated area can vary widely. To exemplify the variation that may occur with a small number of events, in 1997, Greeley County was the least populated county in Kansas with 1,728 residents and Sedgwick County was the largest with 438,679 residents. With 23 deaths occurring in Greeley County in 1997, the crude death rate would be 13.3 deaths per 1,000 population, whereas, 3,434 deaths occurring in Sedgwick County represents a crude death rate of 7.8 deaths per 1,000 population. If five more deaths occurred in each county (e.g., multiple-death accident) Greeley County's crude death rate would increase to 16.2 deaths per 1,000 population. Sedgwick County's crude death rate would increase by only a few hundredths and with rounding, still remain at 7.8 deaths per 1,000 population. Therefore, one must use caution when comparing rates of vital events between counties of significantly different population sizes to avoid misleading conclusions.

Click on your browser's back button to return to the previous page