Methodology is proposed for the design of sequential methods when data
are obtained by gauging articles into groups. Exact expressions are o
btained for the operating characteristics and average sampling number
of Wald sequential probability ratio tests and for the average run len
gth of cumulative sum (CUSUM) schemes based on grouped data. Step-by-s
tep design algorithms are provided to assist the practitioner. The met
hodology is illustrated assuming a normal process with known standard
deviation in which we wish to detect shifts in the mean. An example fr
om a progressive die operation is presented. The methods proposed are
simple to implement and are an economical alternative to variables-dat
a-based sequential sampling plans and CUSUM control charts.