Ballpark Tendencies Chart

[CosmoK]

Can anyone direct me to an explanation of the chart found on the sidebar of the site's main page?

[hqforums]

There is a key at the bottom of the chart. What in particular are you looking for?

[CosmoK]

What I'm looking for ...

... is a explanation of what the chart represents and how it was derived (methodology?). After looking at it and making a few assumptions, some of the rates provided didn't make sense to me. Or I guess I mean they don't make sense relative to what I THOUGHT I KNEW about some of the parks described.

My assumptions are that ...
- the charts represents the deviation from the mean for hitting stats as they were accumulated for each park.
- a +rate is a hitter's advantage
- a - rate is a pitcher's advantage
- the strength/weakness of the home team is obviously a factor in the rating (i.e. a change in the relative strength of a team for the 2003 season would affect the charts current relevance.

One question that really stood out for me was how does or what explains the effects of a ballpark on BBs & Ks??

I'd really like to delve into the analysis that went into it, if it's available.

Thanks ... Mike

[hqforums]

This data is from how STATS Inc. calculates park effects. Their words:

"By comparing the per-game averages (of each stat category) at the home ballpark and on the road, we can evaluate the park's impact. We divide the home average by the road average and multiply the result by 100, generating a park index. If the home and road per-game averages are equal, the index equals 100 and we can conclude that the park had no impact. An index above 100 means that the park favors that particular statistic."

The percentages that appear in the ball park chart just represent the difference from 100, or the per cent variance from the mean (100).