Autocorrelation
To some extent it's what it says: how much something correlates with itself but what...
Abstracteeism
A neologism created by Branca Sa Pires and leapt upon by me in one of...
Attenuation (by unreliability of measurement)
This is the very basic reality that if you have unreliable measures of things, and...
Average absolute deviation (AAD)
This is generally used to describe a family of measures of dispersion, i.e. of the...
Anderson-Darling test
A good test of distribution fit. (That's a graphic from my Rblog post about...
Alternative (alternate) hypothesis
The logical alternative to the null hypothesis in NHST (Null Hypothesis Significance Testing). At...
Anonymisation
This sounds obvious doesn't it and it also seems obvious that clients, and research participants,...
Authenticity Scale (AS)
A twelve item self-report therapy change scale created to reflect Carl Rogers' ideas of authenticity...
Audit, Clinical Audit
In financial terms an Audit refers to a formal inspection of a system or set...
Aggregation
Aggregation in OM refers to the bringing together of data for the purposes of statistical...
Bereavement, grief, loss
Why am I putting this here when it's obviously either too simple to need expansion...
Bowley’s seven-figure summary
One of three "seven-figure" or "seven-number" summaries: i.e. ways of describing a distribution of values...
Bifactor models
A subset of factor analytic models, not to be confused with 2-factor models. Details As with all...
Between group(s) comparison
What it says! Actually, when you see it, it what is really being done...
Bonferroni correction
This is the simplest way to "correct" for the multiple tests problem. Details Read the multiple tests...
Binomial distribution
This probably doesn't come up directly all that often in the therapy/MH literature but it...
Bootstrap methods
A computer intensive statistical method mainly used to obtain robust estimates of confidence intervals around...
Boxplot (or box plot)
Sometimes also called a "box and whisker plot". This is a excellent way to...
Barplot / bar plot
See Histograms and barplots.
Beck Depression Inventory (BDI)
Perhaps the most famous and successful therapy self-report instrument ever. Started with the paper...
Beck Anxiety Inventory (BAI)
The BAI is a (Beck, A. T., Epstein, N., Brown, G., & Steer, R. A....
Bulimia Investigatory Test Edinburgh (BITE)
The BITE is a questionnaire which, as its name suggests, is designed to measure typical...
Between groups tests
The complement to paired, or within person tests. See Paired tests and Between group(s)...
Body Shape Questionnaire (BSQ)
A 34 item self-report measure developed to measure the negative self-appraisal of body shape common...
Bootstrap, Bootstrapping
For our purposes these are modern ways of getting Confidence Intervals around any sample estimate...
Cronbach's coefficient alpha
Despite much criticism, almost all of it criticising people for using Cronbach's alpha without really...
Content validity
This is mainly about typical multi-item nomothetic self-rating questionnaires or rating scales. Content validity...
Cutting points
In our field this refers to scores that are deemed to separate "help seeking" and...
Cluster analysis
Pretty much what it says: a family of statistical methods that look to see if...
Cross-lagged correlation
What it says really! A statistical method that explores the relationship between two variables...
Change vs. outcome
This is just my own pedantry and here to encourage others to think about it...
Covert vs. overt items
The name is pretty accurate: it's about whether items in self-report questionnaires are overt about...
Clinician-reported outcome measures (ClinROMs, CROMs)
These are a subset of Clinical Outcome Assessments (COAs) and were essentially the only change/outcome...
Clinical Outcome Assessments (COAs)
Term used more in the physical health than the psychological health & well-being areas. ...
Censored data
Censored data exists when the value of an observation is not fully known but is...
Classical Test Theory (CTT)
This is one of the two main statistical/mathematical approaches to quantitative psychometrics of the last...
Confidence intervals (CIs)
This is an incredibly useful method. The basic idea is that when you have a...
Chaos, chaos theory
Arts therapists, like many artists and other "creatives" argue that creativity, i.e. the emergence of...
Convergent validity
Part of concurrent validity (q.v.). Convergent validity is evidence that data from a measure...
Concurrent validity
Literally evidence supporting the validity of a measure that is obtained from data obtained at...
Crown-Crisp Experiential Index (CCEI)
Hm, I thought this would be quick and easy but I think it's going...
Composite scores
What it says: making up a score by adding up other things. Despite that...
Centring/Centering
A bit esoteric but you may meet it in reports, particularly those using multi-level modelling...
CORE-14-DD
This is a convenience name for the presentation together of 14 items of the CORE-OM...
Clinically significant change (CSC)
Part of the "Reliable and Clinically Significant Change (RCSC)" methods developed by Jacobson et al. Details I...
Cumulative distribution
It's pretty much what it says: putting the data you have in order so that...
Cramer von Mises test
A good test of distribution fit. (That's a graphic from my Rblog post about...
CORE system
CORE stands for "Clinical Outcomes in Routine Evaluation" and is the the system co-created by...
CORE instruments
Term I use to cover the self-report questionnaires of the CORE system ("CORE measures") together...
CORE measures
These are a set of self-report questionnaires designed primarily to measure change in therapies. ...
Cohen's kappa
Jacob Cohen invented kappa as a way of describing how good agreement was between two...
Confidentiality
Means exactly what it says! Details Confidentiality will be a key issue except in a fairly small...
Central location
A statistic for data from a continuous variable that summarise what it says: central location....
Computer intensive statistics/methods
These are methods that use a lot of computing power and they only really became...
Cell and cell size
Mostly "cell" in statistical work refers to a group of observations sharing two or more...
Controlled trials
These are experiments comparing two or sometimes more groups, typically in our field these involve...
Causality & causal attribution
Perhaps it's understandable that work committed to helping with human misery and self-destructiveness should want...
Clinical/non-clinical
Terms widely used to distinguish a section of the population who may have sufficient problems...
Corrected item-total correlations (CITCs)
This is most used when looking at the psychometric properties of multi-item scales and it...
Categorical/nominal data/scaling
This is about Stevens' typology of scales and it's probably the only bit of his...
Cochrane (collaboration, library)
Cochrane, https://www.cochrane.org/, formerly the Cochrane collaboration, aims to provide high quality, independent evidence in healthcare....
Common factors
This phrase has two meanings in our field: a psychological/therapy one, and a statistical/psychometric one.The...
CORC: Child Outcomes Research Consortium
Leading UK organisation aiming to improve understanding of effective interventions to help young people with...
CORE: Clinical Outcomes in Routine Evaluation
CORE refers both to a set of instruments, i.e. self-rating questionnaire measures and practitioner completed...
Correlation
The statistical meaning of Correlation is not that far from the lay use. If you...
Different approaches to change measurement
This came out of doing some recent additions about change measurement and is a bit...
DBRCT = Double Blind, Randomised Controlled Trial
[This entry overlaps with many others, see links] A randomised controlled trial is a way of...
Derangement(s)
Things are deranged if they are out of order. Interestingly, whether we can put...
DALYs: Disability Adjusted Life Years
OK, time I dived into health economic terms! Details DALYs are an extension of QALYs: Quality...
Dichotomisation
This is the extremely common situation in which we convert a continuous measurement into a...
Domains, dimensions, components and factors
This is my way of clarifying some terms that are often thrown around in psychometrics....
Dose response
One of too many terms that have been pulled across from physical health medicine and...
Descriptive statistics
This covers statistical methods of summarising a dataset that aim only to summarise the data...
Divergent/discriminant validity
With convergent validity, this is part of concurrent validity, it's whether values on a measure...
Data protection
Well of course you'd look after your data wouldn't you? You don't want anyone...
Dispersion
I've been putting this off! It's actually quite a basic idea but it covers...
De-anonymisation
Synonym of re-identification, see, anonymisation, pseudonymisation, confidentiality and smallest identical subset for more on this...
Distribution shape
It's useful to think of distributions of continuous variables in terms of their "central location",...
Discrete measures/variables
A variable that can only take distinct values. Examples might included the locality within a...
Distribution
The frequencies of values for a variable. The term is more often applied to continuous...
Double blind
See "blinding" Details "Double blind" refers to the requirement for idea pharmacological randomised controlled trials that not...
Dependent variable
Though there are statistical methods that handle relationships between many variables, very often we look...
Dataset and database
See sample to read why I think we should be using "dataset" instead of "sample". A...
Efficiency
One of the 3 E’s from the hugely influential monograph: Cochrane, A. L. (1972). Effectiveness...
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...
Ecological Momentary Assessment (EMA)
This refers to collection of data from participants at various times of day in their...
Exploratory factor analysis (EFA)
A statistical approach that hopes to simplify multivariate data, i.e. data where we have values...
European Psychotherapy Consortium (EPoC)
A coalition/consortium arising out of the Society for Psychotherapy Research meeting in 2022 and formalised...
Exploratory data analysis (EDA)
A statistical approach, methodology, inspired by John Tukey. Tukey was something of a polymath...
Eating attitudes test (EAT)
Two self-report questionnaires designed to tap into problematic attitudes common in eating disorders. Details The...
Employee assistance programmes (EAPs)
These are programmes offering some degree of support with mental health and well-being issues for...
Effect size
Effect size measures are a way to separate the strength of an effect. An...
Empirical Cumulative Distribution Function (ECDF)
A cumulative distribution the "empirical" indicates that is based on data not on the definition...
Early termination
Like "attrition" a seemingly polite term for opting out that hides the client's autonomy and...
Empirical research
Any research involving data as well as theory rather than purely exploring theory (conceptual research). Details This...
ECM (Embedded Change Measurement)
As we say in Chapter 1:"We will use ECM to describe the process when OMs...
ESTs (Empirically Supported Treatments)
The name suggests interventions with some evidence base, however it has come to mean therapies...
Expectancy effects
Expectancy effects refer to the power that clients’ and therapists’ and researchers’ beliefs have on...
Estimate, estimation
In statistical thinking we treat a statistic from a sample both as a description of...