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Pythagoran Expectation

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The Pythagorean expectation is a formula created by Bill James that estimates how many games a baseball team is expected to win in a season, based on the number of runs scored and runs allowed (Sportingcharts.com, 2014). James first noticed the non-linear relationship between the number of runs scored, runs allowed and the number of wins, leading him to predict the number of expected wins in baseball (see figure 1 for original formula (Fangraphs.com, 2015). The presence of the sums squared on the numerator and dominator is what prompted Bill James to call the formula the Pythagorean Expectation, however he later revised the formula, changing the exponent from 2 to 1.83. He noted that the exponent of 1.83 predicted the actual number of wins …show more content…

The R2 value is a statistical measurement of how close the data is from the linear regression line and indicates the variation in the values from the relationship of two variables. In graph 1, the R2 value is 0.60497, which indicates a moderate positive correlation. This suggests that around 60% of the variation in the mean age among different football teams can be predicted from the relationship between the number of wins and the mean age of the team. Contrarily, 40% of the variation in mean team ages cannot be …show more content…

A heavier or taller football team could potentially result in a slight advantage when going up in a contest against a smaller player as they have a greater chance of overpowering them. Another factor could simply be the talent and experience of players in a team. If one team has more experienced and talented players than the other, then they will most likely perform better. Although talent would be difficult to measure, experience could be explained by having one player who is 30 years old, but has only played 20 games, whereas a 25 year old player may have player 60 games in their career. The Pythagorean expectation also does not take into account potential injuries that may occur throughout the season. Even though a team may have performed well last season, they may have had several players who had injured themselves, which could in turn affect the teams performance. All these factors could have potentially affected the accuracy of the Pythagorean expectation formula, which highlights how despite the strong correlation between the mean age of the team and the number of games won, this is not the only cause as there are other factors that could have also influenced the

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