The following table shows the number of e-mails a student received each hour from 8:00 a.m. to 6:00 p.m. The samples are collected for five days from Monday to Friday.

(a) Use the rational subgrouping principle to comment on why an XÌ… chart that plots one point each hour with a subgroup of size 5 is not appropriate.

(b) Construct an appropriate attribute control chart. Use all the data to find trial control limits, construct the chart, and plot the data.

(c) Use the trial control limits from part (b) to identify out-of-control points. If necessary, revise your control limits, assuming that any samples that plot outside the control limits can be eliminated.

Transcribed Image Text:

Hour Th 1 3 1 1 1 3 1 1 10