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: the way the search 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 title that is exactly the phrase you typed in to find is hidden down the list of suggestions.

If what 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!

N

Numerical approximation

I think it's pretty unlikely that you will come across this term reading research reports…

Non-inferiority trials/studies

These are extensions of the more conventional randomised controlled trials which usually seek to find…

Numeracy

OK this not a normal entry, it's a cry from the heart! Details So numeracy is ability…

Number Needed to Treat (NNT) and Number Needed to Harm (NNH)

These are very simple ideas coming out of the randomised controlled trial (RCT) world and…

NPV (Negative Predictive Value)

Crucial parameter of any simple screening design: the probability that someone scoring below the screening…

Non-parametric "tests"

Really "non-parametric statistical methods". Statistical methods that don't rely on assumptions about population distributions,…

Null hypothesis significance testing (NHST) paradigm

This, essentially the same as "inferential testing" (q.v.), is the paradigm which has dominated the…

Null hypothesis

This is one of the fundamental building blocks of the "Null Hypothesis Significance Test" (NHST)…

n > 5 rule

See anonymisation!

Notched box plot

[Go to the entry about box plots before this if you are not familiar with…

More

Creation date lost, updated 19.v.24 to add the new BetterDocs “encyclopedia” listing of entries, tweaks 13.iv.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.