Question regarding independent data

[Carlos Méndez <carmende@ufm.edu.gt>]

Rip Stauffer wrote:
> The data should be homogeneous (come from the same process), they should
be
> time-ordered, and they should be independent. Above all, they should be
> selected to be representative of the process. Unless the data meet at
least
> these criteria, charts will be less than useful in studying a process of
> interest.

I wonder what happends when, in the case of batch by batch production, a
supervisor makes adjustmes to a process for the next batch based on the
results of the previous batch. That is a sort of a funnel rule 4. ¿Would
this mean that in this case the data are not independent?

Thanks in advance for any help. Cheers,
Carlos Méndez
INVENIA, S.A.
PBX: (502) 336-9669
invenia@guate.net
Cel: 336-9669

Nunca he tenido la buena suerte de no subirme a un avión que se estrelló.

I have never had the good luck of not abording a plane that crashed.