Final answer:
A study suggesting Starbucks coffee increases lifespan would likely cause a shift in the demand curve to the right, reflecting an increase in demand. This is different from a change in quantity demanded, which is due to a price change. The demand for coffee is inelastic, meaning quantity consumed doesn't change much with price.
Step-by-step explanation:
If Starbucks releases a study suggesting that their coffee increases your lifespan, the change in demand implies that more consumers may desire Starbucks coffee at every price level. This desire is not due to a change in price but rather due to the added health benefit as a factor affecting consumer preferences, leading to a shift in the demand curve to the right. This means there would be a higher quantity demanded at the same price as before the study was released.
This shift is differentiated from a change in quantity demanded, which occurs when the coffee's price itself changes. For example, if the price of Starbucks coffee was lowered to $2, the law of demand tells us more people would buy it since it's cheaper, but that would be a movement along the demand curve, not a shift.
The elasticity of coffee demand significantly impacts these changes. With an elasticity of only about 0.3, a rise in the price of coffee doesn't greatly reduce the quantity consumed, demonstrating inelastic demand. Factors such as new producers entering the market or a frost damaging crops can shift the supply curve, influencing price levels.