6,542 research outputs found
Evaluating Throwing Ability in Baseball
We present a quantitative analysis of throwing ability for major league
outfielders and catchers. We use detailed game event data to tabulate success
and failure events in outfielder and catcher throwing opportunities. We
attribute a run contribution to each success or failure which are tabulated for
each player in each season. We use four seasons of data to estimate the overall
throwing ability of each player using a Bayesian hierarchical model. This model
allows us to shrink individual player estimates towards an overall population
mean depending on the number of opportunities for each player. We use the
posterior distribution of player abilities from this model to identify players
with significant positive and negative throwing contributions.Comment: Accepted for publication in the Journal of Quantitative Analysis in
Sport
Changes in the Distribution of Income Volatility
Recent research has documented a significant rise in the volatility (e.g.,
expected squared change) of individual incomes in the U.S. since the 1970s.
Existing measures of this trend abstract from individual heterogeneity,
effectively estimating an increase in average volatility. We decompose this
increase in average volatility and find that it is far from representative of
the experience of most people: there has been no systematic rise in volatility
for the vast majority of individuals. The rise in average volatility has been
driven almost entirely by a sharp rise in the income volatility of those
expected to have the most volatile incomes, identified ex-ante by large income
changes in the past. We document that the self-employed and those who
self-identify as risk-tolerant are much more likely to have such volatile
incomes; these groups have experienced much larger increases in income
volatility than the population at large. These results color the policy
implications one might draw from the rise in average volatility. While the
basic results are apparent from PSID summary statistics, providing a complete
characterization of the dynamics of the volatility distribution is a
methodological challenge. We resolve these difficulties with a Markovian
hierarchical Dirichlet process that builds on work from the non-parametric
Bayesian statistics literature
Estimating an NBA player's impact on his team's chances of winning
Traditional NBA player evaluation metrics are based on scoring differential
or some pace-adjusted linear combination of box score statistics like points,
rebounds, assists, etc. These measures treat performances with the outcome of
the game still in question (e.g. tie score with five minutes left) in exactly
the same way as they treat performances with the outcome virtually decided
(e.g. when one team leads by 30 points with one minute left). Because they
ignore the context in which players perform, these measures can result in
misleading estimates of how players help their teams win. We instead use a win
probability framework for evaluating the impact NBA players have on their
teams' chances of winning. We propose a Bayesian linear regression model to
estimate an individual player's impact, after controlling for the other players
on the court. We introduce several posterior summaries to derive rank-orderings
of players within their team and across the league. This allows us to identify
highly paid players with low impact relative to their teammates, as well as
players whose high impact is not captured by existing metrics.Comment: To appear in the Journal of Quantitative Analysis of Spor
Does Service Bundling Reduce Churn?
We examine whether bundling in telecommunications services reduces churn using a series of large, independent cross sections of household decisions. To identify the effect of bundling, we construct a pseudo-panel dataset and utilize a linear, dynamic panel-data model, supplemented by nearest-neighbor matching. We find bundling does reduce churn for all three "triple-play" services. However, the effect is only "visible" during times of turbulent demand. We also find evidence that broadband was substituting for pay television in 2009. This analysis highlights that bundling helps with customer retention in service industries, and may play an important role in preserving contracting markets.Bundle, Service, Churn, Triple Play, Telecommunications, Cable, Broadband, Telephone, Screen
Hierarchical Bayesian Modeling of Hitting Performance in Baseball
We have developed a sophisticated statistical model for predicting the
hitting performance of Major League baseball players. The Bayesian paradigm
provides a principled method for balancing past performance with crucial
covariates, such as player age and position. We share information across time
and across players by using mixture distributions to control shrinkage for
improved accuracy. We compare the performance of our model to current
sabermetric methods on a held-out season (2006), and discuss both successes and
limitations
Estimating the Welfare Effects of Digital Infrastructure
While much economic policy presumes that more information infrastructure yields higher economic returns, little empirical work measures the magnitudes of these returns. We examine investment by local exchange telephone companies in fiber optic cable, ISDN lines and signal seven software, infrastructure which plays an essential role in bringing digital technology to local telephone networks. We estimate the elasticity of the derived demand for infrastructure investment faced by local exchange companies, controlling for factors such as local economic activity and the political disposition of state regulators. Our model postulates a regulated profit maximizing local exchange firm and a regulatory agency with predetermined political leanings in favor of consumer prices or firm profits. The model accounts for variation in state regulation and local economic conditions. In all our estimates we find that consumer demand is sensitive to investment in modern infrastructure, particularly as represented by fiber optic cable. Our estimates imply that infrastructure investment is responsible for a substantial fraction of the recent growth in consumer surplus and business revenue in local telecommunication services.
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