In that case the price could rise, but does not need to as the market is sufficiently supplied at a lower price point. A shortage occurs when buyers want to pa

In that case the price could rise, but does not need to as the market is sufficiently supplied at a lower price point. A shortage occurs when buyers want to pay more, and need to pay more for the market to clear, but cannot do so for some reason (the law, for example). A decent indicator of there being a shortage is if the recipient of a product or service is determined by a non-price based mechanism, such as a lottery or a needs-based determination, as the usual 'highest bidder wins' method is not possible.