The survivorship principle is intuitively appealing due to its simplicity and avoidance of unreliable data. However, it also suffers some serious limitations. It is of no help in measuring costs for planning purpose. It merely tells us which company size appears to be more efficient; is says nothing about relative costs. Further, it implicitly assumes the industry is highly competitive so survival and the industry in highly competitive so survival and prosperity are solely a function of efficient use of resources and not of market power or the market power or the erection of barriers to entry. Changing technology and inflation over a long span can also cause distortions. As time passes, the structure of an industry can change in such a way that firms of a certain size are favored over others.