Born in the 1970s as a radical challenge to traditional baseball statistics, sabermetrics has developed into a new way of understanding many aspects of the game. Its practitioners have created new statistical tools and revised our old ways of thinking about established measures such as the batting average, tactics such as the sacrifice bunt, and even who among the greats was truly great. This introduction to the basics of sabermetric analysis explains concepts including normalization, peak versus career performance, linear weights and runs created, as well as popular calculations like OPS (On-Base plus Slugging), WHIP (Walks and Hits per Inning Pitched), PF (Park Factor) and others increasingly used by baseball fans.