  The presence of momentum in sports, where the outcome of a previous event
affects a following event, is a belief often held by fans, and has been the
subject of statistical study for many sports. This paper investigates the
presence and manifestation of momentum in Grand Slam tennis matches from 2014
through 2019 for men and women, to see if there is evidence of any carryover
effect from the outcome of previous point(s)/game(s)/set(s) to the current one
that cannot be accounted for by player quality, fitness or fatigue. Generalized
linear mixed effect models (GLMMs) are used to explore the effects of the
outcomes of previous sets, games, or points on the odds of winning a set, game,
or point, while incorporating control variables that account for differences in
player quality and the current status of the match. We find strong evidence of
carryover effects at the set, game, and point level. Holding one's serve in
prior service games is strongly related to winning a current game, but losing a
past game is associated with higher estimated odds of winning the next game.
Winning the previous two or three points in a row is associated with highest
estimated odds of winning the next point.
