Negative Binomial Regression
A modelling technique analysing count outcome data, such as hospitalisations, that shows overdispersion relative to what a Poisson model would assume.
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Negative Likelihood Ratio
A diagnostic test measure expressing how much a negative result changes the odds a patient does not have the condition tested for.
Negative Predictive Value
The probability that an individual with a negative diagnostic test result truly does not have the condition being tested for.
Net Benefit
A summary measure, in evaluating prediction models, combining the benefit of correctly identifying an outcome against the harm of unnecessary treatment, at a given threshold.
Network Meta-Analysis
A method simultaneously synthesising evidence from connected trials comparing multiple treatments, combining direct and indirect evidence into one set of estimates.
Network Meta-Analysis HTA
The application of network meta-analysis specifically within health technology assessment, generating comparative effectiveness estimates when treatments were never studied together.
Node-Splitting
A technique testing for inconsistency in a network meta-analysis by separately estimating direct and indirect evidence for one comparison and comparing them.
Non-Inferiority Trial
A trial designed to show a new treatment is not meaningfully worse than an active comparator, within a predefined acceptable margin.
Non-Informative Censoring
A form of censoring in which its timing provides no information about a participant's underlying risk, satisfying the assumption standard survival methods require.
Null Hypothesis
In hypothesis testing, the default assumption of no true effect or difference between the groups or conditions being compared.
Number Needed to Harm
The number of patients who would need exposure to a treatment or risk factor for one additional patient to experience an adverse outcome.
Number Needed to Screen
The number of individuals who would need screening for a condition to prevent one adverse outcome, based on prevalence and programme effectiveness.
Number Needed to Treat
The number of patients who would need to receive a treatment for one additional patient to experience a beneficial outcome.
Oblique Rotation
A factor analysis technique transforming a solution into a more interpretable structure while allowing the resulting factors to correlate with each other.
Odds Ratio
A measure comparing the odds of an outcome in one group to the odds in another, common in case-control studies and logistic regression.
One-Stage Meta-Analysis
An individual patient data meta-analysis analysing combined patient-level data from all studies within a single unified statistical model.
One-Tailed Test
A hypothesis test assessing evidence for an effect in only one specified direction, requiring strong prior justification for that direction.
Orthogonal Rotation
A factor analysis technique transforming a solution into a more interpretable structure while constraining the resulting factors to remain uncorrelated.
Outlier
An observation differing markedly from other values in a dataset, either from genuine unusual variation or a measurement or entry error.
Overfitting
A situation in which a model is fit too closely to the noise in its training data, performing poorly on new, independent data.