Design and model based inferences with applications to acidification of lakes in eastern Canada

The design and model based approaches for making inferences about the number of lakes affected by acidic deposition and the chemical characteristics of aquatic resources at risk are described. In many instances when the lakes in the sample are selected for convenience without any randomization, the model based approach continues to provide valid inferences about the population of lakes. The performances of the two approaches are compared using a small population of 177 lakes which are located in southern Quebec. Examples from the Canadian acid rain monitoring program in the Atlantic provinces are also given.