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!

A

Abstracteeism

A neologism created by Branca Sa Pires and leapt upon by me in one of…

Accuracy

What it means in everyday language really. It's one of two parts of observational…

Age

We all know what age is so why put it here?! Because it's a…

Aggregation

Aggregation in OM refers to the bringing together of data for the purposes of statistical…

Alpha

First letter of the Greek alphabet. OK, OK, I know you knew that! It…

Alternative (alternate) hypothesis

The logical alternative to the null hypothesis in NHST (Null Hypothesis Significance Testing). At…

Analysis of covariance (ANCOVA)

A very simple extension of the ANOVA model. Instead of analysing the values of…

Analysis of variance (ANOVA)

This is a huge family of statistical analyses within the NHST (Null Hypothesis Significance Test…

Anderson-Darling test

A good test of distribution fit. (That's a graphic from my Rblog post about…

Anonymisation

This sounds obvious doesn't it and it also seems obvious that clients, and research participants,…

B

Barplot / bar plot

See Histograms and barplots.

Beck Anxiety Inventory (BAI)

The BAI is a (Beck, A. T., Epstein, N., Brown, G., & Steer, R. A….

Beck Depression Inventory (BDI)

Perhaps the most famous and successful therapy self-report instrument ever. Started with the paper…

Bereavement, grief, loss

Why am I putting this here when it's obviously either too simple to need expansion…

Between group(s) comparison

What it says! Actually, when you see it, it what is really being done…

Between groups tests

The complement to paired, or within person tests. See Paired tests and Between group(s)…

Bias

Bias is anything that that results in a conclusion or finding that is not the…

Bifactor models

A subset of factor analytic models, not to be confused with 2-factor models. Details As with all…

Binomial distribution

This probably doesn't come up directly all that often in the therapy/MH literature but it…

Blinding

Blinding refers to concealing or masking group allocation in controlled trials. For example, participants are…

C

Card sort methods

There are a range of card sort methodologies in various disciplines, but they share asking…

Categorical/nominal data/scaling

This is about Stevens' typology of scales and it's probably the only bit of his…

Causality & causal attribution

Perhaps it's understandable that work committed to helping with human misery and self-destructiveness should want…

Ceiling effect

In OM this refers to most people choosing the maximum possible score on an item…

Cell and cell size

Mostly "cell" in statistical work refers to a group of observations sharing two or more…

Censored data

Censored data exists when the value of an observation is not fully known but is…

Census

A true or complete census is a complete dataset about a field of interest. …

Centiles

Synonym of "percentiles" and another name of quantiles really. Chapters Chapter 5 See also Much more detail in the…

Central location

A statistic for data from a continuous variable that summarise what it says: central location….

Centring/Centering

A bit esoteric but you may meet it in reports, particularly those using multi-level modelling…

D

DALYs: Disability Adjusted Life Years

OK, time I dived into health economic terms! Details DALYs are an extension of QALYs: Quality…

Data protection

Well of course you'd look after your data wouldn't you? You don't want anyone…

Dataset and database

See sample to read why I think we should be using "dataset" instead of "sample". A…

DBRCT = Double Blind, Randomised Controlled Trial

[This entry overlaps with many others, see links] A randomised controlled trial is a way of…

De-anonymisation

Synonym of re-identification, see, anonymisation, pseudonymisation, confidentiality and smallest identical subset for more on this…

Degrees of freedom (d.f.)

A key if slightly slippy idea that comes up in a lot of statistical analyses….

Dependent variable

Though there are statistical methods that handle relationships between many variables, very often we look…

Derangement(s)

Things are deranged if they are out of order. Interestingly, whether we can put…

Descriptive statistics

This covers statistical methods of summarising a dataset that aim only to summarise the data…

Diagnosis

Clearly the idea comes out of medicine and what is sometimes called "the medical model"…

E

Early termination

Like "attrition" a seemingly polite term for opting out that hides the client's autonomy and…

Eating attitudes test (EAT)

Two self-report questionnaires designed to tap into problematic attitudes common in eating disorders. Details The…

ECM (Embedded Change Measurement)

As we say in Chapter 1:"We will use ECM to describe the process when OMs…

Ecological fallacy

Rather a pompous but lovely term for a very common mistake. It means assuming…

Ecological Momentary Assessment (EMA)

This refers to collection of data from participants at various times of day in their…

Effect size

Effect size measures are a way to separate the strength of an effect. An…

Effectiveness

One of the 3 E's from the hugely influential monograph: Cochrane, A. L. (1972). Effectiveness…

Efficacy (part of the 3 Es)

My "three E's" are Efficacy, Effectiveness and Efficiency which were the central theme of a…

Efficiency

One of the 3 E’s from the hugely influential monograph: Cochrane, A. L. (1972). Effectiveness…

Eigenvalue

The only places you find this term, which means "own value" from German, is in…

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.