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[28] [29] [30] Fisher suggested a probability of one in twenty (0.05) as a convenient cutoff level to reject the null hypothesis. [31] In a 1933 paper, Jerzy Neyman and Egon Pearson called this cutoff the significance level , which they named α {\displaystyle \alpha } .
Alpha / ˈ æ l f ə / [1] (uppercase Α, lowercase α) [a] is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph, which is the West Semitic word for "ox". [2] Letters that arose from alpha include the Latin letter A and the Cyrillic letter А.
The α-level upper critical value of a probability distribution is the value exceeded with probability , that is, the value such that () =, where is the cumulative distribution function. There are standard notations for the upper critical values of some commonly used distributions in statistics:
In this method, before conducting the study, one first chooses a model (the null hypothesis) and the alpha level α (most commonly 0.05). After analyzing the data, if the p -value is less than α , that is taken to mean that the observed data is sufficiently inconsistent with the null hypothesis for the null hypothesis to be rejected.
To reduce the probability of committing a type I error, making the alpha value more stringent is both simple and efficient. To decrease the probability of committing a type II error, which is closely associated with analyses' power, either increasing the test's sample size or relaxing the alpha level could increase the analyses' power.
Cronbach's alpha (Cronbach's ), also known as tau-equivalent reliability or coefficient alpha (coefficient ), is a reliability coefficient and a measure of the internal consistency of tests and measures. [1] [2] [3] It was named after the American psychologist Lee Cronbach.
Greek letters are used in mathematics, science, engineering, and other areas where mathematical notation is used as symbols for constants, special functions, and also conventionally for variables representing certain quantities. In these contexts, the capital letters and the small letters represent distinct and unrelated entities.
Alpha value (designated α value) may refer to: Significance level in statistics; Alpha compositing This page was last edited on 2 July ...