"Average" vs. rate

[nate]

Perhaps some of the more math inclined peeps can set me straight here. Apologies if this seems like another one of my "streak" threads; I'm not intending it to be!

What I wonder, what does one think of when they hear "batting average?" I know stats like BA, OBP and whatnot are sometimes referred to as "rate stats" but do they really measure rate or do they just measure average after the fact?

For example:
If a player has a .300 average and comes to the plate 10 times does that mean he'll get 3 hits?

OR

If a player has a .300 average and comes to the plate 10 times does that mean he has a 30% chance of getting a hit in each plate appearance?

AND

Is there a difference?

[Scrap Irony]

It measures what has already happened and has no predictive measure.

[jojo]

Perhaps some of the more math inclined peeps can set me straight here. Apologies if this seems like another one of my "streak" threads; I'm not intending it to be!

What I wonder, what does one think of when they hear "batting average?" I know stats like BA, OBP and whatnot are sometimes referred to as "rate stats" but do they really measure rate or do they just measure average after the fact?

For example:
If a player has a .300 average and comes to the plate 10 times does that mean he'll get 3 hits?

OR

If a player has a .300 average and comes to the plate 10 times does that mean he has a 30% chance of getting a hit in each plate appearance?

AND

Is there a difference?

A .300 hitter has gotten a hit 30% of the time.

[BCubb2003]

I suppose that raises the question of whether there are any predictive stats. You'd rather have Joey Votto at the plate than Juan Castro, but what predicts what either will do in this one next instance?

[nate]

It measures what has already happened and has no predictive measure.

I'm not asking if it does.

[LvJ]

I don't see any difference in a guy who is 1-2 in the game already. Doesn't really mean he's going to go 1-2 in his next two ABs.

Would you rather have someone who is 3-10 off a certain pitcher over a guy who is 0-7? On one hand you say, okay... he's had some success. But then you can say, but this other guy is due for a hit. The game of baseball is all about progressing, changing, learning and getting better which is why I hate those batter vs. pitcher stats, or team vs. team stats. I don't believe them to be predictive atall.

[BCubb2003]

A 30 percent chance each time up would tend to have some predictive power, but it's not a weather report. Does he have a 100 percent chance this time up and zero percent the next two times up? But what are all these stats for if not to give you an idea of who you want in a certain situation? Adjusting of course for small sample sizes and the enemy, whose stats get a vote too. Joey Votto's performance, over time, measured in stats, shows we want him instead of Juan Castro.

[cincinnati chili]

Statistics never ASSURE performance in the future, but certain statistics in certain sample sizes can predict the LIKELIHOOD of performance in the future.

Batting average is a type of rate stat. It measures the "rate" of hits per at bat. By contrast, RBIs an HRs are "counting stats."

This guy likes "counting stats" because you don't have to measure them against anything, you can just "count" them:

http://www.youtube.com/watch?v=B-Wd-Q3F8KM

[Scrap Irony]

do they really measure rate or do they just measure average after the fact?

Batting average measures the rate at which a player got a hit?

[nate]

Batting average measures the rate at which a player got a hit?

Does it?

That's what I'm asking. I don't think it does.

[Scrap Irony]

How would it not?

[rdiersin]

Does it?

That's what I'm asking. I don't think it does.

What exactly are you looking for? Are you trying to differentiate between two players: one who gets say 9 hits in 10 abs and then 0 hits in the next 20 from the player who truly averages say 3 hits every 10 abs? If so look at say the standard deviation instead of the mean (average). Otherwise, average is a rate. It is based upon something, in this case 1.0000.

[Ron Madden]

Good to see you posting again rdiersin.

[BearcatShane]

I'm not good at debating all these statitical things in baseball, I'll usually lose. But, I do put stock in average. If a Reds pitcher is facing someone whose had over 150 at bats and his batting average is .308, well I think the guy has a pretty good chance of getting a hit compared to most other players. Maybe he will, maybe he wont, But I think average means something.

[RedsManRick]

Read The Drunkard's Walk. It's a great, accessible primer on statistics and probability.