Industrial Statistics with Minitab

A2.3 Stacking and Unstacking of Columns (File ‘BREAD’)

Consider again file BREAD.MTW already analyzed in chapter six. A detailed description of the steps needed to organize the data in the requested format is given.

The owner of a bakery has detected that some loafs of bread seem to have much less weight than expected. In the bakery, a loaf of bread is produced by two workmen (A and B) using two machines (M1 and M2). The operators do not work simultaneously, but in different days: some days the loafs of bread are produced by operator A using both machines, and some other days by operator B.

The owner of the bakery decides to collect data and carry out an analysis to find out what is causing the problems. For a period of 20 days (10 for operator A and 10 for operator B), four loafs of bread produced by machine one and four produced by machine two are taken at random. The obtained results, included in file BREAD.MTW, are organized as follows:

Column	Contents
C1	Day
C2	Operator
C3	Machine 1 part 1
C4	Machine 1 part 2
C5	Machine 1 part 3
C6	Machine 1 part 4
C7	Machine 2 part 1
C8	Machine 2 part 2
C9	Machine 2 part 3
C10	Machine 2 part 4

The nominal weight for the pieces of bread is 210 g, with a tolerable variation of ± 10 g. The aim is to analyze the collected data to identify what is causing problems.

First, create a column containing the weights ...