A common problem experienced by public health professionals and agencies, especially at the local level, is how to reliably use rates when the number of events being studied are small.
All statistics are subject to chance variation.
However, rates based on an unusually small number of events should be of particular concern and caution. An example of this problem is mentioned below and recommendations on how to cope with it are also discussed. A public health objective is usually stated in terms of reaching a certain point or level over time. An infant death rate is a standard computation and routinely compared over time for achievement purposes. However, for areas with few infant deaths, the statistical unreliability of such a rate can cause problems.