Factor analysis is a variable consolidation technique designed to generate a small number of variables that will capture much of the information in a larger data set. In this way factor analysis allows an investigator to reduce information on frequency of food intake among the members of a study population over the entire range of foods covered by a food frequency
questionnaire (FFQ) into 2 or 3 variables that capture the primary sources of variation in reported diet. These variables, by identifying where the major sources of dietary variation lie, are one way of describing the main dietary patterns in that study population.