base. A later development was the creation of defense independent pitching statistics (DIPS) system. Voros McCracken has been credited with the development of this system in 1999. Through his research, McCracken was able to show that there is little to no difference between pitchers in the number of hits they allow on balls put into play—regardless of their skill level. Some examples of these statistics are defense-independent ERA, fielding independent pitching, and defense-independent component ERA. Other sabermetricians have furthered the work in DIPS, such as Tom Tango who runs the Tango on Baseball sabermetrics website. Baseball Prospectus created another statistics called the peripheral ERA. This measure of a pitcher's performance takes hits, walks, home runs allowed, and strikeouts while adjusting for ballpark factors. Each ballpark has different dimensions when it comes to the outfield wall so a pitcher should not be measured the same for each of these parks. Batting average on balls in play (BABIP) is another useful measurement for determining pitchers’ performance. When a pitcher has a high BABIP, they will often show improvements in the following season, while a pitcher with low BABIP will often show a decline in the following season. This is based on the statistical concept of regression to the mean. Others have created various means of attempting to quantify individual pitches based on characteristics of the pitch, as opposed to runs earned or balls hit. Advanced methods Value over replacement player (VORP) was once considered a popular sabermetric statistic. This statistic demonstrates how much a player contributes to his team in comparison to a hypothetical player that performs at the minimum level needed to hold a roster position on a major league team. This measurement was invented by Keith Woolner, a former writer for the sabermetric group/website Baseball Prospectus. Wins above replacement (WAR) is another popular sabermetric statistic for evaluating a player's contributions to his team. Similar to VORP, WAR compares a given player to a replacement-level player in order to determine the number of additional wins the player has provided to his team. WAR values vary with hitting positions and are largely determined by a player's successful performance and amount of playing time. Quantitative analysis in baseball Many traditional and modern statistics, such as ERA and Wins Shared, don't give a full understanding of what is taking place on the field. Simple ratios are not sufficient to understand the statistical data of