OM book glossary

This is the glossary for the book “Outcome measures and evaluation in counselling and psychotherapy” written by myself and Jo-anne Carlyle and available now from SAGE. I am over 430 entries now and still climbing though now (April 2026) I am concentrating more on harmonising, cleaning up and cross-linking existing entries than I am on adding new ones. Some glossary entries link to more detailed expansions of the topic in my Rblog and, at last, an increasing number now link with interactive online (“shiny”) apps.

You can see the alphabetical list of entries below which is a good place to browse, or you can use this search box.

Beware if you are searching, the way that the plugin orders the matches is to my mind bizarre so scroll down if what you typed isn’t first on the list, you may find something with exactly the word or phrase you typed in to find is hidden further down the list of suggestions. As of 29.ix.26 the plugin authors are aware and working on this.

As to the content, if a topic you want is not there and you think it should be, contact me and tell me and I will put it on the (long!) list of entries to be added!

O

Observation

Can be used in two slightly different ways in our field but in both cases…

Observer-reported outcome measures (ObsROMs, OROMs)

My usual pedantry that we should be very careful about the word "outcome" here and…

Octile(s)

I confess this is me throwing one in for completeness, I don't think I've ever…

Odds = odds ratio

At times in the past I have found the idea of "odds" and odds ratios…

Omitted variable

The is all about summer! OK, it's not generally but the classic explanation of how…

Open access

A fundamental change in the academic publishing world that has exploded in the 21st Century….

Open data

The idea of "open data" is that research papers should put their data into a…

Open peer review

See peer reviewing. Dates Created 18.viii.23.

Open source software

OK, I admit it, this is mostly here to give a plug to the R…

Opting out

More often termed "dropping out" or, mainly by researchers, "attrition". Used to refer to…

More

Creation date lost, last updated 19.ix.26. Author CE; this page and all glossary contents are copyright to me so contact me if you want to quote from them (I’m sure I’ll agree!). That may change to a Creative Commons licence later when I am happier with the content.