Sample data collected by the operator of a lathe process on a part is shown below. The operator took a sample of four parts (n = 4) at seven different points in time. The operator measured the outside diameter of each sampled part and listed the results in the table below. The design specification for this part is 1.250 inches + or - .005 inches.

Samples Taken Over Seven Periods in Time Within Sample Size n = 4 1 2 4 5 6 1.261 1.259 1.239 1.225 1.259 1.255 1.251 1.253 1.263 1.265 1.249 1.243 1.273 1.281 3 1.245 1.247 1.26 1.265 1.242 1.245 1.239 1.249 1.240 1.257 1.248 1.257 1.268 1.245 ave. 1.252 1.252 1.255 1.247 1.250 1.260 1.254LSL USL 1992 1994 1996 1998 2000 2002 2004 2006 2008