What is the K-factor in the Elo Formula — Is it a Mistake?

Arpad Elo designed his rating system back in the 1960’s (possibly late 1950’s). His system replaced the Harkness rating system because the Harkness system exhibited some serious flaws.

This k-factor resides in front of a difference in the formula. Rather than using cryptic English language, I shall be precise: K*(S — E). The K being in this position acts as an amplifier or a dampener. Elo intended for it to be a variable to adjust it for different circumstances. For youth who could improve rapidly, he wanted K to be larger to…