The key concept embedded within the health MDGs is the notion of rate (that is, changes in the level,over time), of some measurable performance indicator. Due to the complexity of objectively demonstrating that rate changes (positive or
negative) have occurred, it is important to have as good a baseline health assessment as possible.
However, it is easier to obtain this information at a country or large regional level than for small populations where the number of measured “events” is small and variable over the standard time period (one year).