W-test - The W-test is an association test developed for categorical genetic data and a binary outcome, including analysis of joint genotype categories for pairs of...
Wait list control group - A wait list control group is a comparison group scheduled to receive an intervention after an initial waiting period, while another group receives it earlier.
Wald test - A Wald test evaluates a parameter restriction by measuring how far an estimated parameter lies from its null value relative to its estimated uncertainty.
Wald - Wolfowitz runs test - The Wald-Wolfowitz runs test examines whether the ordering of a binary sequence is consistent with randomness, commonly conditional on the numbers of each...
Weibull distribution - The Weibull distribution is a flexible continuous distribution for nonnegative quantities, widely used for time-to-event and reliability models.
Weighted average - A weighted average combines values while giving each a specified relative influence.
Weighted model counting - Weighted model counting is the task of summing the weights of all truth assignments that satisfy a logical formula.
Welch's t-test - Welch's t-test compares two population means using independent samples without assuming that the population variances are equal.
Western Electric rules - Western Electric rules are a set of pattern checks used with statistical process control charts to flag possible changes in a process.
Whipple's index - Whipple's index is a demographic measure of concentration in reported ages ending in selected digits, conventionally zero and five.
Whiskers - Whiskers are the lines extending outward from a box in a boxplot.
White test - The White test is a regression diagnostic for heteroskedasticity: variation in error variance across observations.
Whittle likelihood - The Whittle likelihood is a frequency-domain approximation used to estimate parameters of stationary time-series models.
Wide model - A wide model is a linear model with many input features, often represented sparsely, that connect directly to an output score.
Widely applicable information criterion - The widely applicable information criterion, or WAIC, estimates a Bayesian model's out-of-sample predictive performance using pointwise likelihood values...
Wike's law of low odd primes - Wike's law of low odd primes is a deliberately provocative experimental-design maxim associated with a 1973 article by Edward L. Wike.
Wilcoxon signed-rank test - The Wilcoxon signed-rank test evaluates paired differences using the ranks of their absolute sizes together with their signs.
Wilks' theorem - Wilks' theorem states that, under suitable regularity conditions and a true null hypothesis, twice the difference between maximized log likelihoods of...
Win statistics - Win statistics are measures that summarize pairwise comparisons between two groups as wins, losses and ties under a specified outcome rule.
Winsorized samples - Winsorized samples are datasets in which selected extreme observations have been replaced by specified boundary values.
Wizard of Oz experiment - A Wizard of Oz experiment is a user-research method in which a person operates some or all of the functionality that participants experience as an automated...
Wold's theorem - Wold's theorem, in its time-series decomposition sense, states that a covariance-stationary process can be separated into a perfectly linearly predictable...
Working - Hotelling procedure - The Working - Hotelling procedure constructs a simultaneous confidence band for the mean response in a linear regression.
X-bar-R chart - An X-bar-R chart is a paired statistical process-control display that monitors subgroup averages and subgroup ranges over time.
X-bar-S chart - An X-bar-S chart is a paired process-control display that monitors subgroup means and subgroup standard deviations over time.
Yates analysis - Yates analysis is a structured calculation of factor and interaction estimates for suitable factorial experiments, especially two-level designs.
Yates' correction for continuity - Yates' correction for continuity is an adjustment commonly associated with Pearson's chi-square test for a two-by-two contingency table.
Yates's correction for continuity - Yates's correction for continuity is the conventional half-unit adjustment to cell deviations in a two-by-two Pearson chi-square test.
Yoked control design - A yoked control design links the experiences of a control participant to those generated by another participant or experimental unit.
Youden's J statistic - Youden's J statistic summarizes a binary decision rule as sensitivity plus specificity minus one.
Zelen's design - Zelen's design is a randomized study design in which allocation occurs before consent to the assigned study intervention is sought.
Zero degrees of freedom - Zero degrees of freedom means that no independent variation remains for the particular statistical quantity or comparison being considered after its...
Zonal polynomial - A zonal polynomial is a member of a structured family of symmetric, homogeneous polynomials in the eigenvalues of a matrix, indexed by an integer partition.