**StATS: ****Common sources of confusion in a class on quality control (August 22,
2007)**

I presented a training class:

for the American Society for Andrology. The major emphasis was on the computation of control charts. It's always interesting to see how this material goes over. This group was somewhat math-phobic, and felt a certain level of discomfort with the required exercises. Several points of confusion involved

- how to calculate standard deviations with a calculator that does not have a memory,
- some of the data was presented as proportions and some of it was presented as percentages,
- the definition of "n" in the P chart--it is the denominator of the proportions rather than the number of proportions.

You can't expect a class like this to go perfectly, but I will try to pay closer attention to these issues the next time I teach this class.

This page was written by
Steve Simon while working at Children's Mercy Hospital. Although I do not hold the copyright for this material, I am reproducing it here as a service, as it is no longer available on the Children's Mercy Hospital website. Need more
information? I have a page with general help
resources. You can also browse for pages similar to this one at ** **Category: Control charts.