arXiv subjects

Eiji Konaka

Publications and source records attributed to Eiji Konaka.

5 recordsLinked to original sources

arXiv2021

Park factor estimation improvement using pairwise comparison method

Each ballpark has a different size in baseball. It could be easily imagined that there would be many home runs in a small ballpark. Moreover, the environment of the ballpark, such as altitude, humidity, air pressure, and wind strength, affects the trajectory of batted balls. Park Factors (PF) are introduced in baseball to quantify the effect of each ballpark on the results (e.g., home runs). In this paper, I assume that each plate appearance can be modeled as a match-up between a batter's team and a pitcher's team plus a ballpark. The effects of each ballpark will be distilled by using a logistic regression method. Numerical verification shows that the proposed method performs better than conventional PF. The verification is based on the results of more than 1.5 million plate appearances from the 2010 to 2017 Major League Baseball (MLB) seasons.

stat.AP↗

arXiv2021

Can the center lane really have advantages for swimmers?

In swimming competitions, the center lane is considered to be the best lane. The main objective of this study is to discuss the validity of the assertion, "good swimmers should be placed in the center lanes because these lanes has advantage." This study extracts the (positive) lane bias in the center lanes from many records utilizing statistical hypothesis tests. The data is collected from nationwide competitions of Japan over 10 years. The data set contains more than 5900 swimmers and 56000 records. No significant evidence was obtained on the lane advantage of the center lanes.

stat.AP↗

arXiv2021

Home advantage of European major football leagues under COVID-19 pandemic

Since March 2020, the environment surrounding football has changed dramatically because of the COVID-19 pandemic. After a few months' break, re-scheduled matches were held behind closed doors without spectators. The main objective of this study is a quantitative evaluation of ``crowd effects'' on home advantage, using the results of these closed matches. The proposed analysis uses pairwise comparison method to reduce the effects caused by the unbalanced schedule. The following conclusions were drawn from the statistical hypothesis tests conducted in this study: In four major European leagues, the home advantage is reduced in closed matches compared to than in the normal situation, i.e., with spectators. The reduction amounts among leagues were different. For example, in Germany, the home advantage was negative during the closed-match period. On the other hand,in England,statistically significant differences in home advantage were not observed between closed matches and normal situation.

stat.AP↗

arXiv2017

Match results prediction ability of official ATP singles ranking

This paper discusses match result prediction ability of ATP ranking points, which is official ranking points for men's professional tennis players. The structure of overall ATP World Tour and the ranking point attribution system leads that the ranking point ratio between two players is an essential variable. The match result prediction model is a logistic model. The fact is verified using statistics of over 24000 matches from 2009.

stat.AP↗

arXiv2014

Monte-Carlo Simulation of J1 League Postseason System from the 2015 Season

In this paper, the new two stage and postseason system of J1 League, the top division of professional football in Japan, is simulated. Official regulation defines that the new postseason from the 2015 season consists of five teams selected by different principles --- the top three teams by total season points, and the winning teams of the 1st and 2nd half of the season. This paper clarifies that there are overlaps within these five teams and the average number of teams reaching the postseason is about 3.5. The probability that the postseason is held with 3, 4, and 5 teams are estimated about 0.62, 0.35, and 0.03, respectively. From this result, this paper concludes that the new system of J1 League is basically a one-stage system, whereas the new system is officially defined as a two-stage system, due to inappropriate design of the postseason.

stat.AP↗