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The words, before the course.
Short, plain definitions of the terms that turn up in statistics and data science — what they mean, and how they relate to each other. Nothing to sign in for.
32 of 596 entries under A
- A Priori ProbabilityA priori probability is the probability estimate prior to receiving new information. See also Bayes Theorem and posterior probability.
- A-B TestAn A-B test is a classic statistical design in which individuals or subjects are randomly split into two groups and some intervention or treatment is applied – one group gets treatment A, the other treatment B.
- Acceptance RegionIn hypothesis testing, the test procedure partitions all the possible sample outcomes into two subsets (on the basis of whether the observed value of the test statistic is smaller than a threshold value or…
- Acceptance SamplingAcceptance sampling is the use of sampling methods to determine whether a shipment of products or components is of sufficient quality to be accepted.
- Acceptance Sampling PlansFor a shipment or production lot, an acceptance sampling plan defines a sampling procedure and gives decision rules for accepting or rejecting the shipment or lot, based on the sampling results.
- Additive effectAn additive effect refers to the role of a variable in an estimated model. A variable that has an additive effect can merely be added to the other terms in a model to determine its effect on the independent…
- Additive ErrorAdditive error is the error that is added to the true value and does not depend on the true value itself.
- Agglomerative Methods (of Cluster Analysis)In agglomerative methods of hierarchical cluster analysis, the clusters obtained at the previous step are fused into larger clusters.
- Aggregate MeanIn ANOVA and some other techniques used for analysis of several samples, the aggregate mean is the mean for all values in all samples combined, as opposed to the mean values of the individual samples.
- Alpha LevelSee Type I Error.
- Alpha Spending FunctionIn the interim monitoring of clinical trials, multiple looks are taken at the accruing results.
- Alternate-Form ReliabilityThe alternate-form reliability of a survey instrument, like a psychological test, helps to overcome the “practice effect”, which is typical of the test-retest reliability.
- Alternative HypothesisIn hypothesis testing, there are two competing hypotheses – the null hypothesis and the alternative hypothesis.
- Analysis of CommonalityAnalysis of commonality is a method for causal modeling. In a simple case of two independent variables x1 and x2, for example, analysis of commonality posits three sources of causation, described by three…
- Analysis of Variance (ANOVA)A statistical technique which helps in making inference whether three or more samples might come from populations having the same mean; specifically, whether the differences among the samples might be…
- ANOVASee Analysis of variance
- ARIMAARIMA as an acronym for Autoregressive Integrated Moving Average Model (also known as Box-Jenkins model).
- Arithmetic MeanThe arithmetic mean is a synonym of the mean. The word “arithmetic” is used to discern this statistic from other statistics having “mean” in their names, like the geometric mean, the harmonic mean, the…
- Association RulesAssociation rules is a method of data mining. The idea is to find a statistical association between some items in a large set of items, e.g.
- Asymptotic EfficiencyFor an unbiased estimator, asymptotic efficiency is the limit of its efficiency as the sample size tends to infinity.
- Asymptotic PropertyAn asymptotic property is a property of an estimator that holds as the sample size approaches infinity.
- Asymptotic Relative Efficiency (of estimators)Unbiased estimators are usually compared in terms of their variances. The limit (as the sample size tends to infinity) of the ratio of the variance of the first estimator to the variance of the second…
- Asymptotically Unbiased EstimatorAn asymptotically unbiased estimator is an estimator that is unbiased as the sample size tends to infinity.
- AttributeIn data analysis or data mining, an attribute is a characteristic or feature that is measured for each observation (record) and can vary from one observation to another.
- AutocorrelationSee Serial correlation.
- AutoregressionAutoregression refers to a special branch of regression analysis aimed at analysis of time series.
- Autoregression and Moving Average (ARMA) ModelsThe autoregression and moving average (ARMA) models are used in time series analysis to describe stationary time series.
- Autoregressive (AR) ModelsThe autoregressive (AR) models are used in time series analysis. to describe stationary time series.
- Average DeviationThe average deviation or the average absolute deviation is a measure of dispersion. It is the average of absolute deviations of the individual values from the median or from the mean.
- Average Group LinkageThe average group linkage is a method of calculating distance between clusters in hierarchical cluster analysis.
- Average Linkage ClusteringThe average linkage clustering is a method of calculating distance between clusters in hierarchical cluster analysis.
- Azure MLAzure is the Microsoft Cloud Computing Platform and Services. ML stands for Machine Learning, and is one of the services.
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