Final answer:
The primary influence on production and purchasing decisions when drawing demand and supply curves, as assumed by economists, is consumer preferences. Other factors can have an influence, but are not considered primary.
Step-by-step explanation:
When drawing demand and supply curves, economists are making the assumption that the primary influence on production and purchasing decisions is consumer preferences. In economics, consumer preferences dictate demand while producer preferences, such as cost and technological capabilities, dictate supply. However, the interaction of these preferences on a market-wide scale gives us the often depicted demand and supply curves. Other factors, like government regulations, technological advancements, and social media influence can affect both demand and supply, but they are not considered the primary influence when drawing these curves. The primary consideration is always the preferences of consumers and producers.
Learn more about Demand and Supply Curves