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A two-tailed test applied to the normal distribution. A one-tailed test, showing the p-value as the size of one tail. In statistical significance testing, a one-tailed test and a two-tailed test are alternative ways of computing the statistical significance of a parameter inferred from a data set, in terms of a test statistic. A two-tailed test ...
For example, you would use a two-tailed test if one random sample was 15 quarter horses and the second sample was 15 sires or dams of those same horses. A one-tailed test is appropriate if no known relationship exists between the samples, for example, two random samples of 15 unrelated quarter horses. -- 206.208.110.32 20:58, 17 August 2005 ...
The sign test is a statistical test for consistent differences between pairs of observations, such as the weight of subjects before and after treatment. Given pairs of observations (such as weight pre- and post-treatment) for each subject, the sign test determines if one member of the pair (such as pre-treatment) tends to be greater than (or less than) the other member of the pair (such as ...
The difference between the two sample means, each denoted by X i, which appears in the numerator for all the two-sample testing approaches discussed above, is ¯ ¯ = The sample standard deviations for the two samples are approximately 0.05 and 0.11, respectively. For such small samples, a test of equality between the two population variances ...
Most uses of the Fisher test involve, like this example, a 2 × 2 contingency table (discussed below). The p -value from the test is computed as if the margins of the table are fixed, i.e. as if, in the tea-tasting example, Bristol knows the number of cups with each treatment (milk or tea first) and will therefore provide guesses with the ...
In statistics, Dixon's Q test, or simply the Q test, is used for identification and rejection of outliers.This assumes normal distribution and per Robert Dean and Wilfrid Dixon, and others, this test should be used sparingly and never more than once in a data set.
Many animals use their tail for utility purposes, for example many grazing animals, such as horses and oxens, use their tails to drive away parasitic flies and sweep off other biting insects. [6] [7] Some animals with broad, furry tails (e.g. foxes) often wrap the tail around the body as means of thermal insulation like a blanket.
Monotypic taxa present several important theoretical challenges in biological classification.One key issue is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs a distinct definition to maintain logical structure.