Tony is employing a top-down investment approach, which is a method of selecting securities based on macroeconomic factors, such as the state of the economy, the industry trends, and the market conditions. A top-down investor starts by analyzing the big picture and then drills down to the specific sectors, regions, and companies that are expected to perform well in that environment. Tony has done an economic analysis of the various provinces and sectors of the Canadian economy and has determined that Nova Scotia and Alberta present the best prospects. He has also identified potential in the oil and gas sector. He then narrows down his selection to an oil supply firm in Medicine Hat and a drilling company in Halifax. This shows that he is using a top-down approach to choose his investments.