This document discusses demand estimation and forecasting. It notes that demand estimation involves understanding the relationship between demand and its determinants, quantifying the nature of demand, and developing a demand function. The key aspects of demand estimation are identifying dependent and independent variables, developing a mathematical model, collecting primary and secondary data, estimating model parameters, and making estimates based on the model. However, the model cannot be exact due to qualitative consumer behavior. Demand forecasting estimates future demand values based on past data for purposes like production planning, materials purchasing, sales targeting, and financial planning. While useful, demand forecasting has uncertainties since demand depends on many variables and consumer psychology.