What are top-down and bottom-up stock selection?

From bottom to top, it is probably to see a stock strengthen in the stock market. It is a short-term and medium-term stock selection method to analyze what sector to choose from the same sector, that is, individual stocks-sector (industry, concept theme)-select individual stocks. Top-down stock selection is probably based on fundamental factors such as industry sectors and national macro policies, and then individual stocks are selected from sectors, such as RMB appreciation, state-supported agriculture, state-supported energy conservation and environmental protection, and state-supported consumption. It is a medium and long-term stock selection method. Below is the stock, and above is the plate.