Hello all,

Interesting discussion on power normalization. I only want to make one
comment on Stephen Seiler's response.

Whenever we have Likert scales (categories that are numbered), using the
numbers as actually a continuous scale must be done with caution. We know
that 4 is not usually twice 2, etc and therefore the meaning of averages or
medians is not what we would like it to be.

However, there is a way out of the quagmire for those that are interested.
The field of interest is called item-response theory and it basically is a
method of converting the Likert scales to truly continuous scales. This
isn't always necessary, but if you would like to answer Stephen's question
"what is the actual distance between 3 and 4 on the scale, a 7 and 8?", this
is the method that you would use.

Ian Shrier MD, PhD, Dip Sport Med, FACSM
Associate Professor, Dep't of Fam Med, McGill University
Past-president, Canadian Academy of Sport Medicine
check out: www.casm-acms.org

Centre for Clinical Epidemiology and Community Studies
SMBD-Jewish General Hospital
3755 Cote Ste-Catherine Rd
Montreal, Qc H3T 1E2
Tel: 514-340-8222 ext 7563
Fax: 514-340-7564

>-----Original Message-----
>From: sportscience@yahoogroups.com
>[mailto:sportscience@yahoogroups.com]On Behalf Of Stephen Seiler
>Sent: 04-Aug-2006 5:16 AM
>To: sportscience@yahoogroups.com
>Subject: Coggan's power normalization model
>
>
For example, Carl Foster's session RPE scale, which I have
>used to quantify training load both in published studies and practical
>work with Olympic level athletes, is based on a 10 point perceptual
>rating scale with verbal anchors. What is the actual "distance" between
>a 3 and 4 on the scale, a 7 and 8? Don't know.