This document discusses market measurement and forecasting. It explains that marketers measure and forecast the size, growth, and profit potential of market opportunities to identify opportunities and inform decision making. Several methods of measuring the total market, areas within the market, and individual company market share and sales are described, including using total numbers of potential buyers, average purchase quantities and prices, and statistical indices. Demand forecasting is important for production planning, cost control, pricing, and marketing program development. Forecasts rely on past sales data, surveys of intended buyer behavior, expert opinions, and test market results.