CSS Button No Image Css3Menu.com

Baseball Prospectus home
  
  
Click here to log in Click here to subscribe
Glossary Search:

View details for SIERA

View Glossary Entries by

Category:

Report:

Alphabetical:

SIERA

[ Return To Top ]

Skill-Interactive Earned Run Average estimates ERA through walk rate, strikeout rate and ground ball rate, eliminating the effects of park, defense and luck. It adds little value and has been retired from the Baseball Prospectus statistical offerings as of 2011. See Lost in the SIERA Madre for more explanation.

SIERA accounts for how run prevention improves as ground ball rate increases and declines as more whiffs are accrued, while grounders are of more materiality for those who allow a surplus of runners. The formula for SIERA is:

SIERA = 6.145 - 16.986*(SO/PA) + 11.434*(BB/PA) - 1.858*((GB-FB-PU)/PA) + 7.653*((SO/PA)^2) +/- 6.664*(((GB-FB-PU)/PA)^2) + 10.130*(SO/PA)*((GB-FB-PU)/PA) - 5.195*(BB/PA)*((GB-FB-PU)/PA)

where the +/- term is a negative sign when (GB-FB-PU)/PA is positive and vice versa.

This was explained in more detail in the following series: part one, part two, part three, part four, and part five.

It adds little value and has been retired from the Baseball Prospectus statistical offerings as of 2011. See Lost in the SIERA Madre for more explanation.

Show articles tagged with SIERA

SIERA appears in the following BP Glossary Categories:

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