Measure of Variability (MOV) graph
The dots on the graph indicate the county statistic and the vertical lines indicate the county statistic plus and minus the MOV (measure of variability). The MOV is the probable range of values resulting from random fluctuations in the number of events.
Only counties with a calculated MOV appear on the graph. The MOV is not calculated when the numerator is below 5 or the denominator is below 20 because the statistical formulas are not valid for very low numbers.
The MOV is useful for comparing rates to a goal or standard. For example, if the absolute difference between the county rate and the statewide rate is less than the MOV, the county rate is not significantly different from the statewide rate (alpha level = 0.05). When the absolute difference between the county rate and the statewide rate is greater than the MOV, the county rate is significantly different from the statewide rate. MOV should not be used to determine if the rates of two different counties, or the county rates for two different years, are statistically significantly different.