The marginal revenue productivity theory of wages is the change in total revenue earned by a business from employing one more unit of labor. This is also known as marginal revenue product of labor. For a perfectly competitive firm marginal revenue product is equal to marginal physical product multiplied by price. Marginal physical product is the extra unit produced as a result of a new
. employment. For more information visit http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/Labor-Demand-and-Supply-in-a-Perfectly-Competitive-Market.topicArticleId-9789,articleId-9781.html.