# Tags

A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

Statistical analysis of datasets comprising several levels of hierarchy (e.g., students nested in classes nested in schools or hierarchical forecasting). For questions about mixed models use [mixed-mo…
1692 questions
A machine-learning library for Python. Use this tag for any on-topic question that (a) involves scikit-learn either as a critical part of the question or expected answer, & (b) is not just about how t…
1684 questions
Signals situations where one is concerned about achieving intended power and size when more than one hypothesis test is performed.
1676 questions
Descriptive statistics summarize features of a sample, such as mean and standard deviations, median and quartiles, the maximum and minimum. With multiple variables, may include correlations and crosst…
1663 questions
Prediction of unknown random quantities, using a statistical model.
1646 questions
Covariance is a quantity used to measure the strength and direction of the linear relationship between two variables. The covariance is unscaled, & thus often difficult to interpret; when scaled by th…
1592 questions
Autocorrelation (serial correlation) is the correlation of a series of data with itself at some lag. This is an important topic in time series analysis.
1565 questions
The residuals of a model are the actual values minus the predicted values. Many statistical models make assumptions about the error, which is estimated by the residuals.
1555 questions
Probability density function (PDF) of a continuous random variable gives the relative probability for each of its possible values. Use this tag for discrete probability mass functions (PMFs) too.
1551 questions
Usage and meaning of specific technical words/concepts in statistics.
1549 questions
Markov Chain Monte Carlo (MCMC) refers to a class of simulation methods for generating samples from a complex target distribution by generating random numbers from a Markov Chain whose stationary dist…
1453 questions
When the data present lack of information (gaps), i.e., are not complete. Hence, it is important to consider this feature when performing an analysis or test.
1449 questions
for any on-topic question that (a) involves Stata either as a critical part of the question or expected answer, & (b) is not just about how to use Stata.
1430 questions
Parameters associated with the particular levels of a covariate are sometimes called the “effects” of the levels. If the levels that are observed represent a random sample from the set of all possible…
1423 questions
Refers to the standard deviation of the sampling distribution of a statistic calculated from a sample. Standard errors are often required when forming confidence intervals or testing hypotheses about …
1420 questions
Convolutional Neural Networks are a type of neural network in which only subsets of possible connections between layers exist to create overlapping regions. They are commonly used for visual tasks.
1401 questions
Is a property of a hypothesis testing method: the probability of rejecting the null hypothesis given that it is false, i.e. the probability of not making a type II error. The power of a test depends o…
1373 questions
Given a random variable $X$ which arise from a parameterized distribution $F(X;θ)$, the likelihood is defined as the probability of observed data as a function of $θ$: \$\operatorname{L}(θ | x)=\operat…
1363 questions
Cox proportional hazards regression is a semi-parametric method for survival analysis. No distributional form needs to be assumed, only that the effect of one-unit increase in a covariate is a constan…
1329 questions
The relationship between cause and effect.
1327 questions
A regularization method for regression models that shrinks coefficients towards zero, making some of them equal to zero. Thus lasso performs feature selection.
1320 questions
A family of algorithms combining weakly predictive models into a strongly predictive model. The most common approach is called gradient boosting, and the most commonly used weak models are classificat…
1305 questions
Inclusion of additional constraints (typically a penalty for complexity) in the model fitting process. Used to prevent overfitting / enhance predictive accuracy.
1298 questions
A formalization of relationships between stochastically (randomly) related variables in the form of mathematical equations. DO NOT USE THIS TAG BY ITSELF: always include a more specific one.
1292 questions
For statistical topics which involve the assumption of linearity, for example, linear regression or linear mixed models, or for the discussion of linear algebra as applied to statistics.
1291 questions
A stochastic process describes the evolution of random variables/systems over time and/or space and/or any other index set. It has applications in areas such as econometrics, weather, signal processin…
1282 questions
A binary variable takes one of two values, typically coded as "0" and "1".
1275 questions
Events (or random variables) are independent when information on some of them tells you nothing about the probability of occurrence (/ distribution) of the others. Please DO NOT use this tag for indep…
1266 questions
A strictly stationary process (or time series) is one whose joint distribution is constant over time shifts. A weakly stationary (or covariance stationary) process or series is one whose mean and cova…
1260 questions
for any on-topic question that (a) involves MATLAB either as a critical part of the question or expected answer, & (b) is not just about how to use MAT…
1258 questions
Methods focused on contrasting and combining results from different studies, in the hope of increasing precision and external validity.
1245 questions
An outlier is an observation that appears to be unusual or not well described relative to a simple characterization of a dataset. A discomfiting possibility is that these data come from a different po…
1231 questions
'Classification And Regression Trees'. CART is a popular machine learning technique, and it forms the basis for techniques like random forests and common implementations of gradient boosting machines.…
1199 questions
Using (pseudo-)random numbers and the Law of Large Numbers to simulate the random behavior of a real system.
1184 questions
Data mining uses methods from artificial intelligence in a database context to discover previously unknown patterns. As such, the methods are usually unsupervised. It is closely related but not identi…
1174 questions
Usually "normalization" means re-expressing univariate data to make values lie within a specified range.
1140 questions