(Related to the Chapter Opener on page 414) By 2017, McDonald's had stopped selling Chicken McNuggets and other products made from chickens that had been fed antibiotics. The change increased McDonald's costs, but an article in the Wall Street Journal noted that "McDonald's ability to raise its prices is limited because of stiff competition." Does this "stiff competition" mean that the demand curve for McDonald's Chicken McNuggets is horizontal? Briefly explain.

In the world of economics, understanding the elasticity of demand is crucial. It describes how the quantity demanded of a good or service changes in response to a change in its price. The more elastic the demand, the more sensitive consumers are to price changes. In practical terms, if a product has elastic demand, a slight increase in price will lead to a significant drop in the amount that consumers are willing to purchase.

For example, consider the case of fast-food chicken nuggets. If the price goes up and consumers can easily choose a different type of fast-food item, then chicken nuggets have an elastic demand. By contrast, if the price of a life-saving medication that has no substitutes increases, the demand would likely be inelastic, since patients still need it regardless of cost.

When analyzing problems of elasticity, economists use a numerical representation called the price elasticity of demand coefficient, calculated by dividing the percentage change in quantity demanded by the percentage change in price. If this coefficient is greater than 1, the demand is considered elastic; if it is less than 1, it is considered inelastic.

An intriguing and theoretical extreme on the spectrum of elasticity is perfect elasticity. When we say that a demand curve is perfectly elastic, we're imagining a situation in a market where the demand curve is a horizontal line. This implies that consumers are only willing to purchase a good at one specific price, and not a penny more. If the price rises even slightly, the quantity demanded immediately drops to zero.

However, perfect elasticity is more of a theoretical construct than a common real-world scenario. In the case presented in the textbook, despite McDonald's facing intense competition, the demand curve for their Chicken McNuggets isn't perfectly elastic because consumers exhibit a preference for the brand's taste and might tolerate slight price increases.

To illustrate perfect elasticity further, think of a farmer's market where multiple vendors sell identical peaches. If one vendor tries to increase the price, while the others do not, customers will quickly shift to the cheaper options, and the vendor's sales would plummet. This market has characteristics close to perfect elasticity.

Market competition is a force that significantly impacts the elasticity of demand. It refers to the competitive environment in which businesses operate, trying to attract customers by offering better, cheaper, or unique products or services compared to their rivals. High levels of competition can give consumers more choices, thereby making the demand for each individual vendor's product more elastic.

In markets with stiff competition, such as the fast-food industry referenced in the McDonald's Chicken McNuggets scenario, consumers have numerous alternatives. This abundance of choices means that if McDonald's raises its prices, consumers can easily switch to a competitor's product. Yet, competition doesn't uniformly make demand perfectly elastic. Factors such as brand loyalty, product differentiation, and consumer preferences play crucial roles.

It is not merely the existence of competition but the relative strengths and weaknesses of the competitors, along with consumer behavior patterns, that ultimately shape the dynamics of market competition and demand elasticity.