0a) The positional variation occurs (within the specific product)
examples are given below
Within a single unit of production (Chips on the wafer, features of a program)
by position within a batch (cavity to cavity within the mould)
by operator to operator or machine to machine
b) Cyclical variation (between sequential products)
Batch to the batch difference (wafer to wafer)
between consecutive pieces
Between consecutive services (short vs long cycle)
c) Temporal (Shifts over time)
Shift to shift variation
day to day
Set up to set up
