A procedure is proposed for use in evaluating the effect of various control chart procedures. This consists of breaking the power curve associated with a particular control chart technique into four component parts. These are:γ1—probability of undercorrectingγ2—probability of overcorrecting, but still improvingγ3—probability of overcorrecting in excessγ4—probability of adjusting in the wrong directionThese components will be illustrated for a number of situations including Shewhart charts, partial correction procedures, geometrically weighted moving averages, cumulative sums, and an example which includes variability associated with the adjustments and variability in the process before adjustment.