On this page
A regional airline raises ticket prices on a commuter route by 15 percent. If it observes that total ticket revenue increased after the change, it has learned something crucial: demand for those seats is inelastic. Travelers on that route have few alternatives and adjusted their flying plans less than proportionally to the price increase. The airline didn't need to calculate a precise elasticity coefficient to act — the revenue outcome told the story.
The setup
The total revenue test is a practical shortcut for identifying demand elasticity from observed revenue data. It works because the relationship between price, quantity, and total revenue is determined by elasticity:
- Elastic demand (|PED| > 1): quantity responds more than price. A price increase causes a proportionally larger quantity decrease → total revenue falls.
- Inelastic demand (|PED| < 1): quantity responds less than price. A price increase causes a smaller proportional quantity decrease → total revenue rises.
- Unit elastic (|PED| = 1): the effects exactly cancel → total revenue is unchanged.
What happens — and why
Total revenue = P × Q. When price changes, two opposing forces act on revenue: price moves in one direction, quantity moves in the other (law of demand). Which force wins determines what happens to revenue.
For elastic demand: the quantity drop is large enough to overwhelm the price increase. Revenue falls. Think of a luxury item with many substitutes — raise the price 10%, lose 20% of buyers, net revenue declines.
For inelastic demand: the quantity drop is small — buyers have few substitutes or strong need. Revenue rises. Think of insulin — raise the price 10%, lose only 2% of buyers, net revenue increases.
Where you see it in the wild
The U.S. Tobacco Market data from the Centers for Disease Control documents this relationship clearly: cigarette tax increases have consistently raised revenue despite reduced smoking — confirming that demand for cigarettes is inelastic in the short run. Each federal or state excise tax hike simultaneously reduces consumption (a public health benefit) and raises revenue (a fiscal benefit) — possible only when demand is inelastic.
Conversely, airline pricing studies (tracked through the Bureau of Transportation Statistics) show that demand on leisure routes with many competitors is elastic — price cuts by one carrier trigger volume gains large enough to raise revenue, while price hikes cause revenue-reducing passenger defection.
The fix (or why it's hard to fix)
The total revenue test is a diagnostic, not a prescription. It tells a firm or policymaker what has happened to elasticity in a market — it doesn't tell them what price to charge. The optimal price still requires comparing the marginal revenue of another sale against the marginal cost of producing it. The test is most useful as a quick check after a pricing decision to confirm whether the market responded as expected.
