Which of the following is NOT a factor in determining effective purchasing power?

Effective purchasing power refers to the actual ability of consumers to buy goods and services, which is influenced by various factors. Among them, income is critical since it directly affects how much money individuals have available to spend. Economic conditions also play a significant role; for instance, during a recession, purchasing power tends to diminish as people lose jobs or see their income decrease. Similarly, credit availability impacts purchasing power by determining whether consumers can borrow money to make purchases, thus expanding their ability to spend beyond their immediate income.

Investment trends, while they provide insights into the market's direction, do not directly determine an individual's effective purchasing power. They influence the broader economic environment and can impact employment and income levels in the long term, but they do not directly affect a consumer's immediate capacity to purchase goods and services. Therefore, this makes investment trends the correct choice as the factor that does not directly contribute to determining effective purchasing power.