Design and application of a cusum quality control chart suitable for monitoring effects on ultimate muscle pH

摘要

Abstract The cumulative sum, or cusum, chart is introduced for on‐farm monitoring of meat quality traits. The average time over which production is satisfactory or in control (average run length) is defined for the cusum chart and the calculation of this statistic discussed. Data from 9958 Angus and Hereford steers slaughtered at Manawatu Beef Packers (AFFCO) between February 1993 and February 1994 were used to calculate fixed effects and a frequency distribution representing uncontrollable variation in ultimate muscle pH. A cusum chart for on‐farm monitoring of ultimate muscle pH is constructed from this information. A procedure is given for correcting the cumulative sums of unequal sample sizes to a measure suitable for on‐farm monitoring of traits of interest. The role of the cusum chart as an objective tool in farm monitoring programs is discussed, especially for applications of improvement in the quality of carcasses supplied by a farmer to a meat processor.