shifting categories over time
Amy
(75-ish). Data re categorized by "type". (Different respondents,
same questions.)
In year 2008 there were 16 types. In 2010, there were 32 types,
several of which are re-combinations of the 2008 types. I need to
compute a variable "type" that categorizes all the types, where, for
example 2010's TYPE Z is the average of the scores for 2008 TYPE B and
TYPE C.
I want 1 variable that allows me to compare means over time, where
type Z's 2010 data is matched to the average of 2008's average of TYPE
B and C.
Many thanks for your help in advance,
Amy
Ray Koopman
You're setting yourself up for Simpsons's paradox if the relative
number of B's & C's you would have observed in 2010 using the 2008
classification rules differs from the relative weight assigned to the
2008 B & C means when you average them. In general, the only types
that can be compared are those for which the classification rules have
not changed.
Amy
Yes, this makes sense. I had to google Simpson's Paradox, but
remembered it once I did. Many thanks!!
Amy