Stolen Goods: Updating Sample Size! Sample Size! Sample Size!

Courtesy of Derek Carty of The Hardball Times, here is an elaborate update to an older GOI post cataloging the requisite PA thresholds for hitters before certain statistics become statistically significant:

HITTERS

• Strikeout rate/Contact rate: 150 PA
• LD%: 150 PA
• Walk rate: 200 PA
• GB%: 200 PA
• GB/FB: 200 PA
• FB%: 250 PA
• Home run rate: 300 PA
• HR/FB: 300 PA
• BABIP: Doesn't reach a 0.50 r-squared at 650 or below.
• Batting average: Doesn't reach a 0.50 r-squared at 650 or below.
  

PITCHERS

• K/PA: 150 BF
• GB%: 150 BF
• LD%: 150 BF
• FB%: 200 BF
• GB/FB: 200 BF
• K/BB: 500 BF
• IF FB%: 500 BF
• BB/PA: 550 BF
• BABIP: Doesn't reach a 0.50 r-squared at 650 or below.
• HR/FB: Doesn't reach a 0.50 r-squared at 650 or below.

Enjoy.

Sample Size! Sample Size! Sample Size!

When does the "Sample Size" argument become moot for various aspects of a player's hitting line? According to data summarized on Fangraphs.com (originally from this website),

50 PA: Swing %
100 PA: Contact Rate
150 PA: Strikeout Rate, Line Drive Rate, Pitches/PA
200 PA: Walk Rate, Groundball Rate, GB/FB
250 PA: Flyball Rate
300 PA: Home Run Rate, HR/FB
500 PA: OBP, SLG, OPS, 1B Rate, Popup Rate
550 PA: ISO

Cool stuff.