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Where ( ) is the inverse standardized Student t CDF, and ( ) is the standardized Student t PDF. [ 2 ] In probability theory and statistics , Student's t distribution (or simply the t distribution ) t ν {\displaystyle \ t_{\nu }\ } is a continuous probability distribution that generalizes the standard normal distribution .
Most frequently, t statistics are used in Student's t-tests, a form of statistical hypothesis testing, and in the computation of certain confidence intervals. The key property of the t statistic is that it is a pivotal quantity – while defined in terms of the sample mean, its sampling distribution does not depend on the population parameters, and thus it can be used regardless of what these ...
Where n is the total number of scores, and t i is the number of scores in the ith sample. The approximation to the standard normal distribution can be improved by the use of a continuity correction: S c = |S| – 1. Thus 1 is subtracted from a positive S value and 1 is added to a negative S value. The z-score equivalent is then given by
The phrase "T distribution" may refer to Student's t-distribution in univariate probability theory, Hotelling's T-square distribution in multivariate statistics.
The test is based on the work of Michael E. Sobel, [1] [2] and is an application of the delta method. In mediation, the relationship between the independent variable and the dependent variable is hypothesized to be an indirect effect that exists due to the influence of a third variable (the mediator).
From January 2008 to December 2012, if you bought shares in companies when Howard I. Atkins joined the board, and sold them when he left, you would have a -6.7 percent return on your investment, compared to a -2.8 percent return from the S&P 500.
From January 2008 to December 2012, if you bought shares in companies when Charlotte Guyman joined the board, and sold them when she left, you would have a -5.6 percent return on your investment, compared to a -2.8 percent return from the S&P 500.
The t-test p-value for the difference in means, and the regression p-value for the slope, are both 0.00805. The methods give identical results. This example shows that, for the special case of a simple linear regression where there is a single x-variable that has values 0 and 1, the t-test gives the same results as the linear regression. The ...