What does Ttest mean in Stata?
What does Ttest mean in Stata?
The ttest command performs t-tests for one sample, two samples and paired observations. The single-sample t-test compares the mean of the sample to a given number (which you supply). The independent samples t-test compares the difference in the means from the two groups to a given value (usually 0).
What does ha Diff 0 mean?
Ha: mean(diff) > 0. Pr(T < t) = 0.0232. Pr(|T| > |t|) = 0.0463. Pr(T > t) = 0.9768. We find that the means are statistically different from each other at any level greater than 4.6%.
How do you interpret the t-value in a paired t-test?
A t-value of 0 indicates that the sample results exactly equal the null hypothesis. In statistics, we call the difference between the sample estimate and the null hypothesis the effect size. As this difference increases, the absolute value of the t-value increases.
What is significance level in t-test?
The significance level, also denoted as alpha or α, is the probability of rejecting the null hypothesis when it is true. For example, a significance level of 0.05 indicates a 5% risk of concluding that a difference exists when there is no actual difference.
What do t values tell you?
The t-value measures the size of the difference relative to the variation in your sample data. Put another way, T is simply the calculated difference represented in units of standard error. The greater the magnitude of T, the greater the evidence against the null hypothesis.
When to use t tests?
A t-test can be used to compare two means or proportions. The t-test is appropriate when all you want to do is to compare means, and when its assumptions are met (see below). In addition, a t-test is only appropriate when the mean is an appropriate when the means (or proportions) are good measures.
What is the significance of t test?
Definition. A t-test’s statistical significance indicates whether or not the difference between two groups’ averages most likely reflects a “real” difference in the population from which the groups were sampled.
What is t test analysis?
A t-test is an analysis of two populations means through the use of statistical examination; a t-test with two samples is commonly used with small sample sizes, testing the difference between the samples when the variances of two normal distributions are not known.
What is an example of a t test?
Example: Independent samples T test when variances are not equal Problem Statement. In our sample dataset, students reported their typical time to run a mile, and whether or not they were an athlete. Before the Test. Before running the Independent Samples t Test, it is a good idea to look at descriptive statistics and graphs to get an idea of what to expect. Running the Test. Output. Decision and Conclusions.