Latent Growth Model
A modelling framework representing an individual's trajectory using unobserved latent variables for starting level and rate of change, both varying across people.
Encyclopaedia
Explore comprehensive, evidence-informed explanations of key health economics concepts, including their development, application and relationships to other concepts. Published entries are validated through human expert review.
Latent Transition Analysis
A technique modelling how individuals move between unobserved categorical subgroups over time, combining latent class analysis with a longitudinal framework.
Latent Variable
An unobserved, underlying construct inferred from patterns among observed, measurable variables, such as a health dimension inferred from questionnaire responses.
Law of Large Numbers
A theorem stating that as sample size increases, the sample average of a variable converges toward the true underlying population average.
Leave-One-Out
A cross-validation form repeatedly refitting a model using all but one observation, using that observation to test accuracy, until each has served once.
Left Truncation
A survival analysis situation in which individuals are only included once they reach a certain point, such as registry entry, rather than a true start.
Leverage Point
An observation with an unusual combination of predictor values, distinct from the bulk of the data, capable of disproportionately influencing a regression model.
Lifetime Prevalence
The proportion of a population that has experienced a condition at any point in life up to assessment, unlike point prevalence.
Likelihood Ratio
A diagnostic test measure expressing how much a given result, positive or negative, changes the odds that a patient truly has the condition.
Linear Regression
A modelling technique estimating the linear relationship between a continuous outcome and one or more predictors, giving expected change per unit predictor.
Listwise Deletion
A missing data method excluding any observation with a missing value on any variable in an analysis, using only complete cases.
Logistic Regression
A modelling technique estimating the relationship between predictor variables and a binary outcome, expressing results as odds ratios.
Longitudinal Design
A study design following the same individuals over an extended period with repeated measurements, establishing the timing of exposures and outcomes.
Matching-Adjusted Indirect Comparison
A method comparing treatments from separate trials with different populations by reweighting one trial's patient data to match the other trial's reported characteristics.
Maximum Likelihood Estimation
A method estimating a model's parameters by finding the values that make the observed data most probable.
Maximum Likelihood Fitting
The process of applying maximum likelihood estimation to determine the parameter values of a chosen model that best fit observed data.
Mean
A central tendency measure calculated as the sum of a set of values divided by the number of values.
Mean Absolute Error
A measure of average prediction error magnitude between predicted and actual values, calculated without regard to whether errors are positive or negative.
Mean Squared Error
A measure of the average squared difference between predicted and actual values, penalising larger errors more heavily due to squaring.
Measurement Error
Inaccuracy in a recorded value relative to its true value, either random, adding noise, or systematic, consistently over- or under-estimating in one direction.