Power–speed number or power/speed number (PSN) is a sabermetrics

Sabermetrics

Sabermetrics is the specialized analysis of baseball through objective, empirical evidence, specifically baseball statistics that measure in-game activity. The term is derived from the acronym SABR, which stands for the Society for American Baseball Research...

 baseball

Baseball

Baseball is a bat-and-ball sport played between two teams of nine players each. The aim is to score runs by hitting a thrown ball with a bat and touching a series of four bases arranged at the corners of a ninety-foot diamond...

 statistic developed by baseball author and analyst Bill James

Bill James

George William “Bill” James is a baseball writer, historian, and statistician whose work has been widely influential. Since 1977, James has written more than two dozen books devoted to baseball history and statistics...

 which combines a player's home run

Home run

In baseball, a home run is scored when the ball is hit in such a way that the batter is able to reach home safely in one play without any errors being committed by the defensive team in the process...

 and stolen base

Stolen base

In baseball, a stolen base occurs when a baserunner successfully advances to the next base while the pitcher is delivering the ball to home plate...

 numbers into one number.http://www.chesscafe.com/text/heisman23.pdf

The formula is:

.http://www.chesscafe.com/text/heisman23.pdf

(It is the harmonic mean

Harmonic mean

In mathematics, the harmonic mean is one of several kinds of average. Typically, it is appropriate for situations when the average of rates is desired....

 of the two totals.)

Power–speed number is displayed as a number with one digit after the decimal point.

James introduced the power–speed number in his commentary on Bobby Bonds

Bobby Bonds

Bobby Lee Bonds was an American right fielder in Major League Baseball from to , primarily with the San Francisco Giants...

, writing "it is so crafted that a player who does well in both home runs and stolen bases will rate high, and his rating is determined by the balance of the two as well as by the total."http://baseballanalysts.com/archives/2004/07/abstracts_from_15.php

The highest single season power–speed number was turned in 1998 by Alex Rodriguez

Alex Rodriguez

Alexander Emmanuel "Alex" Rodriguez is an American professional baseball third baseman with the New York Yankees of Major League Baseball. Known popularly by his nickname A-Rod, he previously played shortstop for the Seattle Mariners and the Texas Rangers.Rodriguez is considered one of the best...

, then of the Seattle Mariners

Seattle Mariners

The Seattle Mariners are a professional baseball team based in Seattle, Washington. Enfranchised in , the Mariners are a member of the Western Division of Major League Baseball's American League. Safeco Field has been the Mariners' home ballpark since July...

. Rodriguez hit 42 home runs and stole 46 bases to record a power–speed number of 43.9.http://www.baseball-reference.com/leaders/power_speed_number_leagues.shtml

The highest career power–speed number belongs to Barry Bonds

Barry Bonds

Barry Lamar Bonds is an American former Major League Baseball outfielder. Bonds played from 1986 to 2007, for the Pittsburgh Pirates and San Francisco Giants. He is the son of former major league All-Star Bobby Bonds...

. Bonds had 762 career home runs and 514 career stolen bases for a career power–speed number of 613.9. Rickey Henderson

Rickey Henderson

Rickey Henley Henderson is a former Major League Baseball left fielder who played for nine teams from 1979 to 2003, including four stints with his original team, the Oakland Athletics. Nicknamed The Man of Steal, he is widely regarded as the sport's greatest leadoff hitter and baserunner...

 is second on the career list at 490.4, followed by Willie Mays

Willie Mays

Willie Howard Mays, Jr. is a retired American professional baseball player who played the majority of his major league career with the New York and San Francisco Giants before finishing with the New York Mets. Nicknamed The Say Hey Kid, Mays was elected to the Baseball Hall of Fame in 1979, his...

 (447.1), Alex Rodriguez

Alex Rodriguez

Alexander Emmanuel "Alex" Rodriguez is an American professional baseball third baseman with the New York Yankees of Major League Baseball. Known popularly by his nickname A-Rod, he previously played shortstop for the Seattle Mariners and the Texas Rangers.Rodriguez is considered one of the best...

 (410.6), Barry's father Bobby Bonds

Bobby Bonds

Bobby Lee Bonds was an American right fielder in Major League Baseball from to , primarily with the San Francisco Giants...

 (386.0), and Joe Morgan

Joe Morgan

Joe Leonard Morgan is a former Major League Baseball second baseman who played for the Houston Astros, Cincinnati Reds, San Francisco Giants, Philadelphia Phillies, and Oakland Athletics from 1963 to 1984. He won two World Series championships with the Reds in 1975 and 1976 and was also named the...

(385.9).http://www.baseball-reference.com/leaders/power_speed_number_progress.shtmlhttp://research.sabr.org/brj/index.php/thunder-and-lightning