not sensitive enough discriminate between rollers temperature excursions and changes in operating conditions e g feed conditions to provide reliable data relative to rollers the individual control chart on its own was also not sensitive enough to provide a good indicator of the presence of a u201c roller u201d however a combination of the individual control chart mean temperature and mean temperature plus three standard deviations together with a moving range control chart taken over 2 or more thermocouples provided a good method of detecting the presence of these rollers that is when both sets of control limits are exceeded fig1 is a table of plant data compared to the calculations of the present invention showing when rollers had been observed by the plant shaded areas and where they were calculated based on the present invention the value at the bottom right of the table is the average accuracy of the predictive method of the present invention u2014 85 fig1 shows the validation of the process of the present invention however this is likely a minimum because it is calculated using individual thermocouples and it does not discount situation where multiple rollers occurred in the same data set or the fact that at least 3 other thermocouples detected a roller fig2 3 and 4 illustrate the types of events which may be detected by the present invention fig2 shows a series of high speed process temperature measurements showing a typical u201c roller u201d event the chart lines are for different spaced apart thermocouples fig3 shows the high speed process temperature measurements for 1 thermocouple from fig1 note the temperature excursion above the upper control limit ucl for this thermocouple this show one of the conditions for detection.