Changes in the Budget Set
In this section, we explore how the budget set of a consumer shifts with changes in prices and income, influencing the combinations of goods available for purchase. The budget line, which represents all the bundles that can be bought with a given income at prevailing market prices, plays a central role in determining consumer choices.
Impact of Changes in Income
When a consumer's income changes while the prices of goods remain constant, the budget line shifts parallelly either outward (if income increases) or inward (if income decreases). This shift reflects an increase or decrease in the consumption possibilities of the consumer. The equation governing this shift is illustrated as:
$$ p_1 x_1 + p_2 x_2 = M' $$
Here, M' represents the new income. The vertical and horizontal intercepts of the budget line change, corresponding to the new income level, but the slope remains constant since the prices have not changed.
Impact of Changes in Prices
Conversely, when the price of either good changes while income remains constant, the budget line pivots around its intercepts. For instance, if the price of bananas drops, the slope of the budget line becomes less steep, indicating that the consumer can now afford to buy more bananas for the same amount of money while the vertical intercept remains unchanged. This is represented mathematically as:
$$ p_1' x_1 + p_2 x_2 = M $$
where $p_1'$ is the new price of the good.
In both cases, the consumer responds to these changes by adjusting their consumption choices, depending on how price and income elasticity affect their preferences.
This analysis reveals how fundamental changes in economic conditions affect consumer behavior and market dynamics.