Twitter (personal)
Twitter (tennis)

GMAT Hacks
Amazon author page
College Splits
Heavy Topspin
Tennis Abstract
The Summer of Jeff

Jeff Sackmann is an author and entrepreneur who has worked in the fields of sports statistics and test preparation.

In 2007, he co-founded (with Kent Bonham) College Splits, which aggregates amateur baseball data for MLB clubs and NCAA programs.

From 2006 to 2010, he ran Minor League Splits. He once wrote a weekly column for ESPN Insider during the college baseball season, has contributed to The Wall Street Journal, Baseball Prospectus, and appeared on NPR's Morning Edition.

Jeff has written several GMAT textbooks: Total GMAT Math [PDF | print], Total GMAT Verbal [PDF | print], GMAT 111 [PDF | Kindle | print], and a set of 1,800 practice GMAT math problems [PDFs]. Jeff has worked with several major GMAT-prep companies to develop and improve their student resources.

Jeff also dabbles in tennis analytics. He has created Tennis Abstract, publishes tennis research at Heavy Topspin, co-founded (with Ben Rothenberg) the fantasy tennis game Racket Rally, and has contributed to Tennis Magazine, The Wall Street Journal, and

In 2015, he spoke about tennis analytics at the Sloan Sports Analytics Conference and published an extensive database of tennis results, rankings, and stats.

Until he learned that landlords expect rent payments, Jeff was a professional saxophonist and bandleader. He performed with a variety of groups, including his own Oy Christina! jazz orchestra and James Brown's original "funky drummer," Clyde Stubblefield.

Four of his albums are available on Bandcamp, including two with his 15-piece jazz orchestra. He has published many of the complete charts, as well.

From September 2011 to June 2013, Jeff was a full-time traveler, visiting 60 countries and all seven continents. He promises not to write a book about it.