Final answer:
Changes in the prices of essential goods matter more than less important goods. Economists use a weighted average of prices to measure the overall price level.
Step-by-step explanation:
Changes in the prices of goods for which people spend a larger share of their incomes matter more than changes in the prices of goods for which people spend a smaller share of their incomes. For example, an increase in the rental rate on housing matters more to most people than whether the price of carrots rises. To construct an overall measure of the price level, economists compute a weighted average of the prices of the items in the basket, where the weights are based on the actual quantities of goods and services people buy.