CSS Button No Image Css3Menu.com

Baseball Prospectus home
  
  
Glossary Search:

View details for QERA

View Glossary Entries by

Category:

Report:

Alphabetical:

QERA

[ Return To Top ]

QuikERA (QERA) estimates what a pitcher's ERA should be based solely on his strikeout rate, walk rate, and GB/FB ratio.

These three components--K rate, BB rate, GB/FB--stabilize very quickly, and they have the strongest predictive relationship with a pitcher's ERA going forward. What's more, they are not very dependent on park effects, allowing us to make reasonable comparisons of pitchers across different teams.

Formula:
QERA(unscaled) =(2.69+K%*(-3.4)+BB%*3.88+GB%*(-0.66))^2

Then, QERA is scaled to league average.
QERA(scaled) = QERA(unscaled) / League ERA * League QERA

Note that everything ends up expressed in terms of percentages: strikeouts per opponent plate appearance, walks per opponent plate appearance, and groundballs as a percentage of all balls hit into play. If, for example, Andy Pettitte has a 19.6% K rate, a 7.9% BB rate, and a 62.7% GB rate, he would have a QERA of 3.68. Note further that QERA is exponential, which is appropriate since run scoring is not linear.

Learn more in this article by Nate Silver.

QERA appears in the following BP Glossary Categories:

Baseball Prospectus Home  |  Terms of Service  |  Privacy Policy  |  Customer Service  |  Newsletter  |  Masthead  |  Contact Us

Copyright © 1996-2014 Prospectus Entertainment Ventures, LLC.