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Showing posts from October, 2007

NESSIS Presentation on Volleyball

Just about a month ago, Harvard hosted the inaugural New England Symposium on Statistics in Sports ( official site , news release ). In perusing the abstracts of conference papers (which can be accessed through the conference website, where it says "Program"), I came across a study (presented in poster format) entitled, "Skill Importance in BYU Women’s Volleyball: A Bayesian Approach." The authors were BYU statistics graduate student Lindsay Florence and professor Gilbert Fellingham . The beginning of the abstract gives the basics of the study: The BYU womens volleyball team recorded all skills (pass, serve-receive, set, etc.), rated each skill, and recorded rally outcomes (point for BYU, rally continues, point for opposition) for the entire 2006 home volleyball season. Only sequences of events occurring on BYU's side of the net were considered. Florence and Fellingham were nice enough to e-mail me a PDF of their poster. It conveys some basic statistic

Overview of Defense: Blocking and Digging

Continuing our series on the different skills and facets of volleyball, our topic today is defense against opponents' spike attempts, namely blocking and digging . As always, it's a good idea to look at the formal definitions of these plays, for statistical purposes. According to AVCA guidelines , blocks "are awarded when a player blocks the ball to the opposition's court leading directly to a point without a successful dig." As elaborated in the guidelines, blocks are credited as solo or assist, according to certain criteria. Also, the hitter who is blocked in the manner described above receives an attack error. A dig "is awarded when a defensive player keeps a bona fide attack in play with a pass." The central inquiry motivating this blog, of course, is what can be learned through measurement and statistics that tells us about winning matches. Given the suggestion in an earlier posting that a team's hitting percentage seems to be a good

JQAS Article on Serve Reception, Setting, and Attack

A new issue of the online publication, the Journal of Quantitative Analysis in Sports , was announced today. Among the articles was one on volleyball by researchers from Greece, entitled "Does Effectiveness of Skill in Complex I Predict Win in Men’s Olympic Volleyball Games?" The authors made a terminological distinction between "complex I (serve reception, setting, attack)" and "complex II (serve, block/defense, counterattack)" sequences, and focused on analyzing the former. Raters evaluated videotaped game footage with a software system, issuing grades (on a 0-4 scale) on serve reception and first attack (setting was not graded). Not surprisingly, high-level execution of both reception and attack were associated with winning. The authors used discriminant analysis , which is among the more complex techniques in the data analyst's arsenal. I would have liked to see more basic statistics, such as means and frequencies with, respectively, t-tests

Overview of Serving and Serve Receipt

Today, let's take up serving and serve receiving , which appear to be two sides of the same coin. Box-score statistics tend to be quite limited, generally reporting only service aces and errors, and serve reception errors. Jim Coleman's chapter in Shondell and Reynaud's Volleyball Coaching Bible (which I've referenced previously) summarizes some schemes for grading serves and serve reception. The schemes appear to have both a spatial component -- with short serves, in the center of the receivers' court on the left-right dimension, being considered poor for the server and advantageous for the receiver, and deep serves the opposite -- and a component for how likely the receiving team would be to generate an attack for a side-out, given the placement of the ball. Consistent with calls for better statistical graphics in volleyball, I had been thinking of serve placement/receipt charts, modeled after shot charts in basketball (see examples here and here ). A

Overview of Setting

Following up on the previous entry about hitting, we now take up another indispensable part of the offense, the setting . This Daily Californian article from about a year ago describes the setter's role through the eyes of Cal-Berkeley setter Samantha Carter, who at the time was finishing up her four-year career leading the Golden Bears' offense. The following excerpts give an idea of what being a setter entails: “You have to be one of the better athletes — you’re doing more running and jumping than anyone else on the team,” says Bears coach Rich Feller... “You have to be a sponge and be able to absorb other players’ mistakes and take it upon yourself to make things better.” ... Before each play, Carter will make eye contact with all of her hitters and signal to them to designate where they’ll each be going and what the play is. Throughout the play, she vocally communicates with her teammates on the court. “First thing, when I give my calls I basically try to think,

Overview of Hitting Percentage

For my next few postings, I would like to provide initial examinations of the major volleyball statistics, to try to get a feel for them. Let's start with hitting percentage (also called attack percentage), which can be computed for either individual players or teams. For a player or a team, one totals the number of kills (i.e., successfully putting the ball away on an attempted attack), then subtracts the number of hitting errors (e.g., attack attempts hit out of bounds or into the net, or that get blocked back into the hitter's face for an opponent's point). The remaining number is then divided by total attack attempts. These terms are defined rigorously on this document from the American Volleyball Coaches Association. Imagine the following different hypothetical performances. One player, whom we might call "Dana Devastator" has the ball set up for her 10 times and successfully puts it away all 10 times. That would be a 1.000 performance ([10-0]/10)