The MVPMONITOR Procedure

Getting Started: MVPMONITOR Procedure

Subsections:

Creating a Multivariate Control Chart in a Phase I Situation

This example illustrates the basic features of the MVPMONITOR procedure by using airline flight delay data available from the U.S. Bureau of Transportation Statistics at http://www.transtats.bts.gov. The example applies multivariate process monitoring to flight delays, and it is a continuation of the example in the section Getting Started: MVPMODEL Procedure.

Suppose you want to use a principal component model to create $T^2$ and SPE charts to monitor the variation in flight delays. These charts are appropriate because the data are multivariate and correlated.

The following statements create a SAS data set named MWflightDelays, which provides daily average delays by airline for flights that originated in the midwestern United States. The data set contains variables for nine airlines: AA (American Airlines), CO (Continental Airlines), DL (Delta Airlines), F9 (Frontier Airlines), FL (AirTran Airways), NW (Northwest Airlines), UA (United Airlines), US (US Airways), and WN (Southwest Airlines).

data MWflightDelays;
   format flightDate MMDDYY8.;
   label flightDate='Date';
   input flightDate :MMDDYY8. AA CO DL F9 FL NW UA US WN; 
   datalines; 
02/01/07 14.9  7.1  7.9  8.5 14.8  4.5  5.1 13.4  5.1
02/02/07 14.3  9.6 14.1  6.2 12.8  6.0  3.9 15.3 11.4
02/03/07 23.0  6.1  1.7  0.9 11.9 15.2  9.5 18.4  7.6
02/04/07  6.5  6.3  3.9 -0.2  8.4 18.8  6.2  8.8  8.0
02/05/07 12.0 14.1  3.3 -1.3 10.0 13.1 22.8 16.5 11.5
02/06/07 31.9  8.6  4.9  2.0 11.9 21.9 29.0 15.5 15.2
02/07/07 14.2  3.0  2.1 -0.9 -0.6  7.8 19.9  8.6  6.4
02/08/07  6.5  6.8  1.8  7.7  1.3  6.9  6.1  9.2  5.4 
02/09/07 12.8  9.4  5.5  9.3 -0.2  4.6  7.6  7.8  7.5
02/10/07  9.4  3.5  1.5 -0.2  2.2  9.9  3.1 12.5  3.0 
02/11/07 12.9  5.4  0.9  6.8  2.1  7.9  3.7 10.7  5.6
02/12/07 34.6 15.9  1.8  1.0  4.5 10.2 14.0 19.1  4.9
02/13/07 34.0 16.0  4.4  6.1 18.3  9.1 30.2 46.3 50.6
02/14/07 21.2 45.9 16.6 12.5 35.1 23.8 40.4 43.6 35.2
02/15/07 46.6 36.3 23.9 20.8 30.4 24.3 30.3 59.9 25.6
02/16/07 31.2 20.8 15.2 20.1  9.1 12.9 22.9 36.4 16.4
;

The observations for a given date are the average flight delays in minutes for flights that departed from the midwestern United States. For example, on February 2, 2007, F9 (Frontier Airlines) flights departed 6.2 minutes late on average.