Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site water.UUCP Path: utzoo!watmath!watnot!water!abgamble From: abgamble@water.UUCP (abgamble) Newsgroups: net.sport.baseball Subject: Re: World Series Probabilities Message-ID: <843@water.UUCP> Date: Sun, 22-Sep-85 14:48:12 EDT Article-I.D.: water.843 Posted: Sun Sep 22 14:48:12 1985 Date-Received: Mon, 23-Sep-85 00:44:21 EDT References: <538@lasspvax.UUCP> Distribution: net Organization: U of Waterloo, Ontario Lines: 54 > In preparing a text on probability for nonscientists, a professor of ours > considered the possibility that the teams were equally likely to win, and > computed the probabilities that the Series would go 4, 5, 6 or 7 games based > on this assumption. > Using the above assumption, the chance of a Series of a given length can be > calculated; comparing with data from 1926-1975, we find > > 1926-50 Calculation 1951-1975 > 7-games 7 7.8 15 > 6-games 5 7.8 3 > 5-games 7 6.2 4 > 4-games 6 3.1 3 > > The 15 7 game Series lies more than 3 standard deviations away, and the 3 > 6 game Series is over 2 standard deviations away. > > To explain this anomaly we decided to test the assumption that the home team > advantage was the cause. > ... In the last 30 years, the team which started the Series at > home went on to win it 21 times ... > ... this 21/30 ratio > corresponds to a .87 probability of winning a home game. > > We don't have statistics for individual games; this should be checked > by those who can and are interested. Any other information relating > to these issues would be appreciated. > > Dan Rokhsar > Eric Grannan Between 1951 and 1975 there were 155 World Series games played. The home team won 89 (57%) of those games, far short of the 87% you guessed. I think a far more plausible explanation for all the long series, is pitching. The strength of a team (the probability they will win) varies a great deal depending on who their starting pitcher is. For an extreme example, see the 1972 Phillies. Thus if you have one "hot" starter, you may have an 70% chance of winning game 1, but only a 30% chance of winning game 2. More examples, - In the 1975 W.S., the Red Sox were 3-0 when Luis Tiant started, and 0-4 in the other games. - During the 1960's, St. Louis was involved in the W.S. three times. The Cardinals were 7-2 in games Bob Gibson started, and 4-8 otherwise. Whether or not this explains the large number of 7-game series, I don't know, but at the very least I think it's an important point you've overlooked. -- Bruce Gamble - abgamble@water.UUCP