Interpreting the XmR charts

Let’s talk a bit about terminology.

You may find some texts referring to normal variation as “routine variation.” These same texts may also call abnormal variation by the term “exceptional variation.” Don't worry, the meaning of these terms is the same as presented in this eBook.

One interesting study that you may wish to perform is to compare your actual casino results with computer perfect play.

Signals for Abnormal Variation

Ø  A single value beyond the Limits

Ø  2 out of 3 consecutive values beyond Sigma 2

Ø  3 out of 4 consecutive values closer to one of the limits than to the central line

Ø  4 out of 5 consecutive values beyond Sigma 1

Ø  6 or more consecutive values steadily increasing or decreasing

Ø  7 out of 8 consecutive values to one side of center 7

Ø  8 points in a row outside plus or minus Sigma 1

Ø  14 points in a row that alternate direction

Ø  15 points in a row within plus or minus Sigma 1

Ø  Too few runs

Ø  Too many runs

Any time you detect a signal, then you will want to immediately determine the “special cause.” Let’s now discuss each of the signals for abnormal variation so that you will know what to look for in your own data.

Signal 1: A single value beyond the Limits

Whenever you have a win or loss that is outside the limits you will know to look for the ''special cause,” or reason.

lf we take a look at Player A’s results in Figure 12.6, we see an example of Signal 1 being invoked.

 © 2009 Norman Wattenberger