Final answer:
Buyer Behaviour research focused on demand must consider factors such as tastes and preferences, income, prices of related goods, and population size or composition, as these significantly influence consumer purchasing decisions.
Step-by-step explanation:
Buyer Behaviour research that focuses on demand must consider several key factors that influence a consumer's decision to purchase a product or service. Demand is defined as the amount of some product a consumer is willing and able to purchase at each price. One of the chief factors affecting demand is a consumer's tastes and preferences, indicating their willingness to purchase. A person will not buy a product if they neither need nor want it. Moreover, a consumer's ability to purchase is determined by their income, which dictates what they can afford.
Prices of related goods also play a significant role in determining demand. If the price of one good, like a Honda, is high, it may lead to increased demand for another, like a Ford. Lastly, the size or composition of the population greatly affects demand; for instance, a large family will have a higher demand for clothing and possibly car insurance, but a lower demand for baby supplies.