Specific language impairment (SLI) is diagnosed when a child's language does not develop normally and the difficulties cannot be accounted for by generally slow development, physical abnormality of the speech apparatus, autism spectrum disorder, acquired brain damage or hearing loss.
Perfect competition. A perfectly competitive market is a hypothetical market where competition is at its greatest possible level. Neo-classical economists argued that perfect competition would produce the best possible outcomes for consumers, and society.
Such markets are allocatively efficient, as output will always occur where marginal cost is equal to marginal revenue (MC = MR). But perfectly competitive markets are not necessarily productively efficient as output will not always occur where marginal cost is equal to average cost (MC = AC).