Log likelihood - Log likelihood is the logarithm of a likelihood function, usually using the natural logarithm.
Log-linear models - Log-linear models describe expected counts by making their logarithms linear combinations of parameters.
Logistic regression - Logistic regression is a statistical and machine-learning method for modeling the probability of a categorical outcome.
Logrank test - The logrank test compares time-to-event distributions between groups while allowing right-censored observations.
Long-range dependence - Long-range dependence is persistent statistical dependence across widely separated observations in a time series or another indexed process.
Longitudinal or serial data - Longitudinal or serial data contain repeated measurements of a response on the same subject or unit over time.
Longitudinal study - A longitudinal study follows the same subjects or units over time, collecting observations that reveal change, continuity, and the ordering of events.
Lot quality assurance sampling - Lot quality assurance sampling, or LQAS, is a sampling approach used to classify a lot, service area, or other defined group against quality or performance...
Lusser's law - Lusser's law states that the reliability of a series system equals the product of its component reliabilities when component survival events are...
Magnitude of effect - Magnitude of effect describes how large a difference or association is, rather than simply whether it is statistically detectable.
Mail survey - A mail survey collects information through questionnaires sent to selected respondents by postal mail, usually for them to complete and return themselves.
Main effect - A main effect is the effect of one factor averaged across the levels of other factors in a factorial analysis.
Maintenance-free operating period - A maintenance-free operating period, or MFOP, is a specified period during which a system is intended to perform its required functions without maintenance...
Manipulation check - A manipulation check is a measurement used in an experiment to assess whether an intervention changed the condition, perception, or psychological state that...
Mann-Whitney U test - The Mann-Whitney U test is a rank-based statistical test for comparing two independent samples.
Mantel test - A Mantel test assesses association between two matrices of pairwise distances or dissimilarities measured on the same set of objects.
Marchenko - Pastur distribution - The Marchenko - Pastur distribution describes the limiting distribution of eigenvalues of certain large sample covariance matrices when the number of...
Marginal distribution - A marginal distribution is the probability distribution of one variable, or a selected subset of variables, obtained from a joint distribution by accounting...
Marginal probability - A marginal probability is the probability of an event or variable value without restricting other variables in a joint probability model to particular values.
Marginal structural model - A marginal structural model is a model for features of the distribution of potential outcomes under specified interventions or treatment histories.
Marginal totals - Marginal totals are the sums for the categories of one variable after adding across the categories of another variable in a table.
Markov logic network - A Markov logic network, or MLN, combines first-order logical formulas with numerical weights to define a probabilistic model over relationships and attributes.
Masking - Masking, in comparative-study design, means keeping specified people unaware of which intervention, condition, or treatment a participant receives.
Master sample - A master sample is a sample selected for use on multiple future survey occasions, rather than drawing a completely new sample independently for every inquiry.
Matched samples - Matched samples are samples whose observations have a meaningful correspondence across conditions or groups.
Matched-samples t test - A matched-samples t test, also called a paired t test, tests a hypothesis about the population mean of differences between paired numerical observations.
Matching pursuit - Matching pursuit is a greedy algorithm that approximates a signal or vector by repeatedly selecting a dictionary element that closely matches the current...
Matrix variate Dirichlet distribution - A matrix variate Dirichlet distribution is a probability distribution for several random matrices that generalizes familiar scalar Dirichlet and matrix beta...
Matthews correlation coefficient - The Matthews correlation coefficient, or MCC, measures agreement between predicted and observed class labels using the full confusion matrix.
Mauchly's sphericity test - Mauchly's sphericity test assesses a covariance assumption commonly used in univariate repeated-measures analysis of variance.
Maximum entropy - Maximum entropy is a principle for choosing a probability distribution that has the greatest entropy among distributions satisfying specified constraints.
Maximum likelihood estimate - A maximum likelihood estimate is a parameter value, or set of values, that maximizes the likelihood of the observed data within a specified statistical model.
MCA - MCA means measurement capability assessment, also called measurement capability analysis, in the supplied NIST statistical glossary.
Mean - The mean, usually meaning the arithmetic mean, is the sum of a set of numerical values divided by the number of values.
Mean absolute deviation (m.a.d.) - Mean absolute deviation is the average absolute distance of observations from a specified center.
Mean Absolute Error - Mean Absolute Error, or MAE, is the arithmetic mean of the absolute differences between predictions and their corresponding observed or reference values.
Mean absolute percentage error - Mean absolute percentage error, or MAPE, averages the absolute prediction error relative to each observation's actual value.
Mean average precision - Mean average precision, often written MAP or mAP, is an average of average-precision scores over evaluation units such as search queries or object categories.
Mean directional accuracy - Mean directional accuracy, or MDA, is the proportion of evaluated forecasts that correctly predict the direction of a specified change.
Mean opinion score - A mean opinion score, or MOS, is an average of ratings assigned on a predefined opinion scale in a quality-evaluation study.
Mean Percentage Error - Mean Percentage Error, or MPE, is the arithmetic average of signed forecast errors expressed as percentages of the corresponding actual values.
Mean pooling - Mean pooling is an operation that combines a collection of equally sized vectors by averaging their corresponding coordinates.
Mean Squared Error - Mean Squared Error, or MSE, is the average of squared differences between observed values and corresponding predictions.
Mean squared logarithmic error - Mean squared logarithmic error, or MSLE, is the average squared difference between the natural logarithms of one plus each actual value and one plus its...
Mean time to failure - Mean time to failure, or MTTF, is the expected operating time until a defined failure for an item or population under specified conditions.
Measurement error - Measurement error is the difference between a measured value and an appropriate reference value.