Another issue with the traditional measure of the batting average is that it does not distinguish between hits (i.e., singles, doubles, triples, and home runs) and gives each hit equal value. Thus, a measure that differentiates between these four hit outcomes, the slugging percentage, was created. To calculate the slugging percentage, the total number of bases of all hits is divided by the total numbers of time at bat. Stephen Jay Gould proposed that the disappearance of .400 batting average is actually a sign of general improvement in batting. This is because, in the modern era, players are becoming more focused on hitting for power than for average. Therefore, it has become more valuable to compare players using the slugging percentage and on-base percentage over the batting average.