Elasticity — common mistakes

When calculating PED, always show your workings clearly. State the formula, substitute the values, and then interpret the result in the context of the business. For example, explain why a PED of -0.4 is price inelastic and what this means for the firm's revenue if they change the price.

In evaluation questions, link elasticity concepts to other parts of the syllabus, such as marketing (pricing strategies), operations (production levels), and finance (revenue forecasting). For example, 'A high YED for its luxury cars means the business is vulnerable to economic downturns, which could impact its cash flow forecast and ability to fund planned expansion.'

State sign of PED (usually negative) but compare absolute value to 1 for elastic/inelastic.

Not necessarily. While a steep demand curve looks inelastic, elasticity actually changes along a straight-line demand curve. At high prices (top of the curve), demand is elastic, while at low prices (bottom of the curve), it becomes inelastic. The gradient is constant, but the ratio of price to quantity changes. Therefore, you must calculate the PED value at a specific point or over a specific price change rather than just judging by the steepness of the entire curve.

Yes, for a standard good, PED is always negative because price and quantity demanded have an inverse relationship (as price goes up, demand goes down). However, for interpretation, we are interested in the magnitude of the response. We use the absolute value (ignoring the minus sign) to classify demand as elastic (>1) or inelastic (<1). A value of -2.5 is more elastic than -0.5. The negative sign is assumed, but the focus is on the number itself to guide pricing strategy.

No, elasticity values are not static. They are a snapshot at a particular point in time and at a particular price level. Factors that determine elasticity, such as consumer tastes, income levels, the number of competitors, and technology, are constantly changing. A successful business must periodically re-estimate the elasticity of its products to ensure its pricing and marketing strategies remain effective and responsive to current market conditions.