Nolan Madson writes:
>I have a data set of answers to questions on employee performance.
>The answers available are:
>
>Exceeded Expectations
>Met Expectations
>Did Not Meet Expectations
>
>The answers can be assigned weights of 3,2,1 (Exceeded, Met, Did Not
>Meet).
>
>One of my colleagues says that it is not valid to average categorical
>data such as this.
This is one of those debates that almost takes on a religious overtone. I
would not be terribly offended to see a mean reported for this data, though
the gap between "Met" and "Did Not Meet" is typically a larger gap than
between "Met" and "Exceeded". The "Did Not Meet" rating is typically
reserved for those people that a supervisor would like to fire. Other people
get quite upset about this, though.
You could get some buy-in to an average by first asking any critic what
their grade point average was. Unless they respond with a statement like
"73% of my grades were B or higher" you have them in a contradictory
response.
The grade point average is an average of data that is clearly ordinal and
where (in my humble opinion) the gap between a "D" and an "F" is much larger
than the gap between an "A" and a "B".
If a grade point average is considered valid then you might ask how would it
differ from the above employee rating scale.
Of course, you should read what Deming and others say about employee rating
systems, but that is a topic for a different email.
If I were doing this project, I would try to get a sense of the folks who
will be reading your report. Are they nit pickers? If so, avoid an issue
like averaging ordinal data that would give them an extra nit to pick at. Or
are they people who despise details and yearn for simplicity. Then use an
average which provides a single numeric summary that has a simple (perhaps
overly simple) interpretation.
And I wouldn't put a lot of time into this problem, since that would tend to
add legitimacy to a system (numerical rating of employees) that deserves no
legitimacy.
Steve Simon, Steve Simon, [EMAIL PROTECTED], Standard Disclaimer.
STATS: STeve's Attempt to Teach Statistics. http://www.cmh.edu/stats
Watch for a change in servers. On or around June 2001, this page will
move to http://www.childrens-mercy.org/stats
=================================================================
Instructions for joining and leaving this list and remarks about
the problem of INAPPROPRIATE MESSAGES are available at
http://jse.stat.ncsu.edu/
=================================================================
