H-spread - The H-spread is the difference between the upper and lower hinges of a dataset.
Hadamard transform - The Hadamard transform represents a signal using patterns built from plus and minus signs rather than sinusoidal waves.
Hahn estimator - In quality-control terminology, the Hahn estimator estimates outgoing nonconformance from acceptance-sampling data while allowing underlying lot quality to...
Hajek projection - The Hájek projection of a finite-variance statistic based on independent observations is its best mean-square approximation within the class of additive...
Half-normal distribution - The half-normal distribution describes the absolute value of a normally distributed variable centered at zero.
Hallucination - In AI, a hallucination is generated content that is false, unsupported or inconsistent with the information it is supposed to reflect, often presented...
Hamiltonian Monte Carlo - Hamiltonian Monte Carlo, or HMC, is a Markov chain Monte Carlo method for sampling from continuous probability distributions using gradients of their log...
Hamming - Hamming is a name attached to several distinct concepts, including Hamming distance, Hamming loss, Hamming codes, and the Hamming window.
Hamming distance - Hamming distance counts the positions at which two aligned sequences of equal length contain different symbols.
Hamming loss - Hamming loss measures the fraction of individual label decisions that are incorrect.
Hampel test - A Hampel test, commonly called the Hampel identifier, flags observations that lie unusually far from a median relative to a robust estimate of spread based...
Handwriting recognition - Handwriting recognition is the process of converting handwritten marks into machine-readable text or symbols.
Hankel transform - The Hankel transform is an integral transform using Bessel functions that is especially useful for problems with radial or cylindrical symmetry.
Hannan - Quinn information criterion - The Hannan - Quinn information criterion is a score for comparing statistical models that balances goodness of fit against model complexity.
Hard attention - Hard attention is an attention mechanism that makes a discrete selection of input information, such as choosing one image region or a small set of positions...
Hard clustering - Hard clustering is clustering where every item belongs to exactly one cluster, with no partial or shared membership: each customer, document or transaction...
Hard expectation maximization - Hard expectation maximization, or hard EM, fits a latent-variable model by replacing uncertainty about hidden variables with selected assignments and then...
Hard privacy technologies - Hard privacy technologies are privacy-enhancing approaches designed to reduce the need to trust a data holder by technically limiting what information that...
Hard Sigmoid Function - The hard sigmoid function is a piecewise-linear activation that approximates the S-shaped logistic sigmoid using a straight middle segment and flat lower...
Harking - HARKing means hypothesizing after the results are known and presenting the resulting hypothesis as though it had been proposed before examining those results.
Harmful bias - Harmful bias is a systematic pattern in an AI system or its surrounding process that contributes to unjustified disadvantage, exclusion, misrepresentation...
Harmonic Centrality - Harmonic centrality measures a node's accessibility by adding the reciprocals of shortest-path distances between it and other nodes.
Harmonic function - A harmonic function is a sufficiently smooth scalar function whose Laplacian is zero within a region.
Harmonic mean - The harmonic mean of positive numbers is the reciprocal of the arithmetic mean of their reciprocals.
Harmonic mean estimator - The harmonic mean estimator is a method for estimating a Bayesian model's marginal likelihood from posterior samples by taking the harmonic mean of their...
Harmonization - Image harmonization adjusts the appearance of image elements so they look visually consistent when combined.
Harris corner detector - The Harris corner detector identifies image locations where brightness changes strongly in more than one direction.
Hartley's test - Hartley's test, also called the F-max test, tests whether several normally distributed populations have equal variances by comparing the largest sample...
Hartley transform - The Hartley transform is a real-valued transform closely related to the Fourier transform.
Haseman - Elston regression - Haseman - Elston regression is a family of statistical-genetics methods connecting similarity in quantitative traits with genetic sharing between pairs of...
Hash-based structure - A hash-based structure organizes data using a hash function that maps a key to a bucket, slot, or other lookup location.
Hash function - A hash function maps an input to a compact value used for purposes such as indexing, comparison, or verification.
Hash join - A hash join is a database execution method that uses a hash table to find matching rows between inputs, commonly for equality-based join conditions.
Hashing - Hashing is the conversion of data of any size into a fixed-length code, called a hash, so that items can be stored, compared, retrieved or anonymized...
Hashtag - A hashtag is a label formed by placing the hash symbol, #, before a word or unspaced phrase in a service that recognizes this syntax.
HATEOAS - HATEOAS stands for Hypermedia as the Engine of Application State.
Hausdorff distance - Hausdorff distance measures the greatest nearest-neighbor separation between two sets of points.
Hawthorne effect - The Hawthorne effect refers to a change in behavior or responses arising because people know they are being observed or studied.
Hays - Efros scene completion - Hays - Efros scene completion is a research approach that fills missing image regions by retrieving compatible content from a very large photograph collection.
Hazard rate - A hazard rate is the instantaneous rate at which an event occurs at time t among units that have not yet experienced it.
Hazard ratio - A hazard ratio compares the instantaneous event rates of two groups among members who remain event-free at a particular time.
HBJ model - The HBJ model, named for Helman, Bader and JáJá, is a cost model for analyzing parallel algorithms on message-passing machines.
HDR (high dynamic range) - HDR, or high dynamic range, describes imaging representations or systems that handle a broad range between dark and bright values.
HDR merging - HDR merging combines multiple measurements of the same scene to produce an image representation with useful information across a wider brightness range.
HDR-VDP - HDR-VDP is a family of visual-difference prediction methods designed to estimate how people perceive differences between images across a broad luminance range.
Head - A head is a model component that performs a particular computation or produces a particular kind of output.
Head/tail breaks - Head/tail breaks is a classification method that repeatedly divides data around their arithmetic mean, focusing the next division on the smaller group of...
Healing brush - A healing brush is an image-retouching tool that replaces unwanted local detail while adapting the replacement to the surrounding appearance.