Latent Class Analysis
A technique identifying unobserved, categorical subgroups within a population from patterns of responses, assuming these fully explain the observed associations.
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Latent Class Model
A statistical model that assumes a population consists of unobserved subgroups with distinct preferences, estimating both each subgroup's traits and individual membership probability.
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.
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.
Latin Hypercube Sampling
A sampling technique dividing each input's range into equally probable intervals and sampling each exactly once, giving more even coverage than simple random sampling.
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.
Least Squares Approximation
A method of estimating a model or function by minimising the sum of the squared differences between observed and predicted values.
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 Censoring
A form of censoring in which an event is known to have occurred before an observed time, but its exact prior timing is unknown.
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.
Life Expectancy
The average number of years an individual of a given age is expected to live, based on current age-specific mortality rates.
Life Table
A tabular record of a population's mortality experience, showing the probability of death at each age and the resulting survivors over time.
Life Table Method
A survival technique dividing follow-up into fixed intervals and calculating the proportion of at-risk patients surviving each, accounting for censoring.
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.
Likelihood Ratio Test
A statistical test comparing the fit of two nested models by their ratio of likelihoods, used to judge whether added parameters improve fit.
Linear Interpolation
A method of estimating values between two known data points by assuming a straight-line relationship between them.
Linear Model Health
A statistical or decision-analytic model in which inputs and outputs are related by a simple linear function, such as a constant per-unit cost.