Analysis of Marshall's measure of consumer's surplus
Consumer's surplus is a measure of the economic welfare that consumers gain from consuming a good or service at a price lower than what they are willing to pay. Marshall's measure of consumer's surplus is based on the concept of the demand curve and the area between the demand curve and the price level.

Assumption of perfect competition
When analysing Marshall's measure of consumer's surplus, one typically assumes perfect competition. In perfect competition, there are many buyers and sellers in the market, all products are homogeneous, and there are no barriers to entry or exit. This assumption allows for a clear and straightforward analysis of consumer surplus based on the intersection of the demand curve and the price level.

Implications of perfect competition
Under perfect competition, the demand curve represents the marginal benefit that consumers receive from consuming an additional unit of a good or service. The consumer surplus is then calculated as the area between the demand curve and the price level, up to the quantity consumed. This represents the value that consumers receive above and beyond what they actually pay for the good.

Significance of the assumption
Assuming perfect competition allows for a simplified and intuitive analysis of consumer surplus, as it provides a clear framework for understanding the relationship between price, quantity, and consumer welfare. While real-world markets may not always exhibit perfect competition, this assumption helps to illustrate the concept of consumer surplus in a practical and accessible way.