Park effect formula

StyxNCa · 12-14-2008, 11:20 PM

Does anyone know how the effect for each category is calculated? I read it someplace years ago but forgot where I saw it.

Garlon · 12-14-2008, 11:57 PM

I created all of the historical park factors myself for OOTP9. It was weeks and weeks of work. I used the park data from retrosheet to calcualte the discreet park factors of BA/2B/3B/HR for all parks 1956-present. The park factor each year is actually calculated based on 5 years worth of data with the focus year being half the weight in the analysis. This is how Bill James created his park factors when he created Win Shares. So to see calculate the HR factor for instance you find the HR/AB rate for what a team and their opponent did in the home park and compare it to the HR/AB of what that team and their opponent did on the road.

We don't have 2B and 3B data pre-1956, but we do have Run Scoring data. From the Run Scoring data I had to create a custom formula that involved the Quadratic Formula to create a modifier that could be applied to BA and HR in order to relicate the impact of scoring in each ballpark each season. The variables that go into the Quadratic are different each season for each league.

PhillieFever · 12-15-2008, 06:56 AM

Quote:

Originally Posted by Garlon

I created all of the historical park factors myself for OOTP9. It was weeks and weeks of work. I used the park data from retrosheet to calcualte the discreet park factors of BA/2B/3B/HR for all parks 1956-present. The park factor each year is actually calculated based on 5 years worth of data with the focus year being half the weight in the analysis. This is how Bill James created his park factors when he created Win Shares. So to see calculate the HR factor for instance you find the HR/AB rate for what a team and their opponent did in the home park and compare it to the HR/AB of what that team and their opponent did on the road.

We don't have 2B and 3B data pre-1956, but we do have Run Scoring data. From the Run Scoring data I had to create a custom formula that involved the Quadratic Formula to create a modifier that could be applied to BA and HR in order to relicate the impact of scoring in each ballpark each season. The variables that go into the Quadratic are different each season for each league.

From a historical player like myself,you work has truely been appreciated,thank you.

StyxNCa · 12-15-2008, 11:28 AM

Quote:

Originally Posted by Garlon

I created all of the historical park factors myself for OOTP9. It was weeks and weeks of work. I used the park data from retrosheet to calcualte the discreet park factors of BA/2B/3B/HR for all parks 1956-present. The park factor each year is actually calculated based on 5 years worth of data with the focus year being half the weight in the analysis. This is how Bill James created his park factors when he created Win Shares. So to see calculate the HR factor for instance you find the HR/AB rate for what a team and their opponent did in the home park and compare it to the HR/AB of what that team and their opponent did on the road.

We don't have 2B and 3B data pre-1956, but we do have Run Scoring data. From the Run Scoring data I had to create a custom formula that involved the Quadratic Formula to create a modifier that could be applied to BA and HR in order to relicate the impact of scoring in each ballpark each season. The variables that go into the Quadratic are different each season for each league.

Ah, ok. Thanks.

Buane · 12-15-2008, 11:55 AM

I have a question somewhat related to this question. What kind of scale are park factors in the game on? For example, a factor of 1.100 for HRs means what % increase in homeruns? The manual states that it is not a straight percentage change, so I know it's not 10% more.

I ask because I put together some charts for a league that I'm in, and I tried to adjust the numbers to account for ballpark. Unfortunately, not knowing the approximate percentage change as related to park factors means I had to guess at the effect.

If anyone knew this it would be a big help.

Garlon · 12-15-2008, 04:59 PM

HR are on a per AB basis

2B and 3B are on a per non-HR hit basis.

An offensive park will not only produce more runs, but it will also produce more AB. So if the HR factor is higher relative to the other parks in the league that can turn the lineup over more frequently to, which wll in turn generate more HRs.

StyxNCa · 12-16-2008, 12:03 PM

Quote:

Originally Posted by Garlon

HR are on a per AB basis

2B and 3B are on a per non-HR hit basis.

An offensive park will not only produce more runs, but it will also produce more AB. So if the HR factor is higher relative to the other parks in the league that can turn the lineup over more frequently to, which wll in turn generate more HRs.

I'm a bit confused. Why couldn't HR's be based on a hit basis? How does the game engine actually translate all of thefactors, on a hit basis, AB basis? Is the BA factor the factor for singles or the overall BA?

Do I ask too many questions?

Syd Thrift · 12-16-2008, 01:12 PM

simple answer: the DIPS engine.

Garlon · 12-16-2008, 01:56 PM

It might actually be HR per hit. I did it all a year ago. I'd have to go back and look at my notes.

12-14-2008, 11:20 PM	#1
StyxNCa Hall Of Famer Join Date: Dec 2004 Location: Victoria, Texas Posts: 3,136	Park effect formula Does anyone know how the effect for each category is calculated? I read it someplace years ago but forgot where I saw it.

12-15-2008, 11:55 AM	#5
Buane Minors (Double A) Join Date: Mar 2006 Posts: 163	I have a question somewhat related to this question. What kind of scale are park factors in the game on? For example, a factor of 1.100 for HRs means what % increase in homeruns? The manual states that it is not a straight percentage change, so I know it's not 10% more. I ask because I put together some charts for a league that I'm in, and I tried to adjust the numbers to account for ballpark. Unfortunately, not knowing the approximate percentage change as related to park factors means I had to guess at the effect. If anyone knew this it would be a big help. __________________ Commissioner - Rising Star League Congratulations to the 2060 Champion Buffalo Rangers!

12-14-2008, 11:57 PM	#2
Garlon Hall Of Famer Join Date: Jun 2004 Posts: 4,170	I created all of the historical park factors myself for OOTP9. It was weeks and weeks of work. I used the park data from retrosheet to calcualte the discreet park factors of BA/2B/3B/HR for all parks 1956-present. The park factor each year is actually calculated based on 5 years worth of data with the focus year being half the weight in the analysis. This is how Bill James created his park factors when he created Win Shares. So to see calculate the HR factor for instance you find the HR/AB rate for what a team and their opponent did in the home park and compare it to the HR/AB of what that team and their opponent did on the road. We don't have 2B and 3B data pre-1956, but we do have Run Scoring data. From the Run Scoring data I had to create a custom formula that involved the Quadratic Formula to create a modifier that could be applied to BA and HR in order to relicate the impact of scoring in each ballpark each season. The variables that go into the Quadratic are different each season for each league.

12-15-2008, 04:59 PM	#6
Garlon Hall Of Famer Join Date: Jun 2004 Posts: 4,170	HR are on a per AB basis 2B and 3B are on a per non-HR hit basis. An offensive park will not only produce more runs, but it will also produce more AB. So if the HR factor is higher relative to the other parks in the league that can turn the lineup over more frequently to, which wll in turn generate more HRs.

12-16-2008, 01:56 PM	#9
Garlon Hall Of Famer Join Date: Jun 2004 Posts: 4,170	It might actually be HR per hit. I did it all a year ago. I'd have to go back and look at my notes.