The stability of a rate is dependent on the number of events that contribute to that rate. Therefore, rates in small populations are often unstable due to the relatively small number of events that occur each year. When comparing trends over time between Middlesex-London, the province and the Peer Group, we often see a larger fluctuation in rates locally than for Ontario, in which the trends are fairly smooth from year to year – this concept needs to be considered when interpreting the time trends and the confidence intervals in this resource.