In a game of inches, where immortals may only be separated from ulility players by a few percentage points, it is essential to know how to calculate these averages.

1. Batting Average

This is the most common benchmark for judging a hitter's effectiveness. It's also easy to calculate. Just take the number of hits a player has and divide that number into the total number of at-bats that he has. Unless the player has gotten a hit every time up, the number will be a decimal that is well below 1.000.

The Formula: Hits divided by At Bats. (Round the number to three places after the decimal point).

Example: Derek Jeter has 59 Hits in 163 At-Bats.

Apply Formula: 59 divided by 163 = .362.

That's right. As of May 19, 2007, Derek Jeter's batting average is .362. It is not necessary to acknowledge the decimal point when discussing batting averages. Simply saying "362" will be understood by all baseball fans.

2. On Base Percentage

This ratio takes into account a player's (a) hits, (b) times he reached base by walk; and (c) times getting hit by a pitch. Some say this average is more indicative of a batter's total value as a hitter because it factors in every time that a hitter reaches base safely, not just the time the batter gets a hit.

The Formula

(a) Add Hits + Walks + Times Hit by Pitch (This sum is the total Times on Base)

(b) Calculate Total Plate Appearances by adding At Bats (AB), Walks (BB) and times Hit by Pitch (HBP)

(b) Then divide sum A (Times on Base) into Sum B (Total Plate Appearances)

Example:

Let's use Derek Jeter again.

(a) He has 59 hits + 19 Walks + 4 HBP, which equals 82 Times on Base.

(b) Calculate Jeter's Total Plate Appearances -- 163 AB + 19 BB + 4 BB -- which is 186.

(c) Divide 82 Times on Base by 186 Total Plate Appearances, and the ratio is .440.

So, Derek Jeter has an On-Base Percentage (OBP) of .440 as of May 19, 2007.

3. Slugging Percentage.

This is designed to measure not just a player's ability to get hits, but also his penchant for getting extra base hits, including home runs.

Formula: Total Bases divided by At-Bats.

Example: Alex Rodriguez has 25 singles, 9 Doubles, 0 Triples and 16 Home Runs in 159 At-Bats

To calculate his slugging percentage, first calculate A-Rod's Total Bases.

(a). (25 Singles times 1 Total Base per Single) = 25

(b). (9 Doubles times 2 Total Bases per Double) = 18

(c). (16 Home Runs times 4 Total Bases per HR) = 64

(d). 25 + 18 + 64 = 107 Total Bases.

Then divide A-Rod's Total Bases into His Total At-Bats

107 Total Bases divided by 159 At-Bats, which equals .673.

So, as of May 19, 2007, Alex Rodriguez has a .673 Slugging Percentage.

4. On-Base Plus Slugging (OPS)

This is a relatively new statistic created by Boston Red Sox statistical consultant Bill James. It is designed to merge a player's OBP, which measures how often he gets on base, and his Slugging Percentage (which measures ability to hit for average and power). Many baseball epxerts believe that this statistic is the most comprehensive and accurate measure of a player's ability to produce at the plate.

The Formula

On Base Percentage plus Slugging Percentage

How to Calculate:

(a) Calculate the player's On-Base Percentage;

(b) Calculate the player's Slugging Percentage.

(c) add (a) + (b).

Example: Using A-Rod again, calculate his OBP (Times on Base divided by Total Plate Appearances)

(a) Times on Base - 50 Hits + 17 BB + 6 HBP, which equals 73 Times on Base.

(b) Total Plate Appearances - 159 AB + 17 BB + 6 HBP, which equals 182 Total Plate Appearances.

Which equals a .397 OBP.

Then, take A-Rod's Slugging percentage, which as calculated earlier, is .673.

Then, add the two numbers to figure Alex's OPS: .673 + .397 = 1.070 OPS.