An estimated one-quarter of the workforce is employed in marketing, transportation, and related distribution activities, making the general field of marketing one of the largest areas of employment opportunity in business today. Marketing, the activities related to the movement of goods and services from producer to consumer, consists of advertising, consumer behavior, marketing management, product development, retailing, and sales management. The field integrates the understanding of economics, sociology, psychology, and statistics to develop marketing systems and processes, and applies this knowledge to specific marketing management problems.