park factors 1871-2008
The version of the browser you are using is no longer supported. Please upgrade to a supported browser.Dismiss

ABCDE
1
2
3
PF_R: Park Factor for Runs
4
PF_HR: Park Factor for HR
5
PADJ_R: Park Adjustment for Runs. This is the number you would use to adjust a team/player's composite statistics that include both home and road games.
6
PADJ_HR: Park Adjustment for HR. This is the number you would use to adjust a team/player's composite statistics that include both home and road games.
7
8
Notes
9
10
1. The Park Factors are based upon a 5-year moving average, unless there are fewer than 5 years available.
11
2. Outs for most years prior to 1954, are estimated using the average number of outs per home/away win, loss, and tie, and then reconciled to the total number of league outs on a yearly basis.
12
3. Interleague games were removed from 1997-2008.
13
4. These Park Factors do not correct for unbalanced scheduling.
14
5. Each franchise is assigned a new Park Factor version when:
15
a. They move into a new stadium.
16
b. The dimensions of their current stadium are significantly altered.
17
c. They play a signficant amount of a season(s) in 2 stadiums. For instance, the Brooklyn Dodgers playing 15 games in New Jersey in 1956 and 1957.
18
19
Methods:
20
21
1. Dividing Runs per Out at Home by Runs Per Out on the Road for all of the seasons that fall under the PF Version. Do the same for HR.
22
2. Correct for the offset of other parks in the league. This is the initial Park Factor (iPF)
23
3. Apply regression using Mitchell Lichtman's equations. This is the final Park Factor
24
For 1 year: 1-(1-iPF)*.6
25
For 2 years: 1-(1-iPF)*.7
26
For 3 years: 1-(1-iPF)*.8
27
For 4 years: 1-(1-iPF)*.9
28
For 5 years: 1-(1-iPF)*.95
29
4. Calculate the Park Adjustment (PADJ) from the final Park Factor. This adjustment takes into account the fact that a team plays half of it's games at home and half on the road.
30
31
Formulas: (Substitute HR for R when calculating the HR PF)
32
33
aPF = (Runs Home / Outs Home) / (Runs Away / Outs Away)
34
iPF = aPF * ((N_Teams) / ((N_Teams - 1) + aPF))
35
PF = 1 - (1 - iPF) * Regression Rate
36
Regression Rate is .6 for 1 year, .7 for 2 years, .8 for 3 years, .9 for 4 years, and .95 for 5 years
37
PADJ = (Outs Away + (Outs Home * PF)) / (Outs Home + Outs Away)
38
39
Credits:
40
41
Retrosheet, which is the primary source for most of the data in these spreadsheets
42
KJOK for the park homerun information from 1871-1953
43
Brian Cartwright for providing his Park Configurations table which I ended-up modifying.
44
Mitchel Lichtman for the regression equations.
45