# T-Test: What It Is, Multiple Formulas, and When To Use Them.

T-Test: Multiple Formulas and When To Use Them What is the difference between ANOVA and t-test? Both ANOVA and t-test are statistical methods used to compare two or more groups. ANOVA is used to compare groups when the dependent variable is continuous and the groups have equal variances. t-test is used to compare groups when the dependent variable is continuous and the groups have unequal variances.

##### What is t-test and Z test what is it used for?

A t-test is a statistical test that is used to determine whether two samples are significantly different from each other. The t-test is also known as the Student's t-test, and is used when the sample size is small and the population variance is unknown.

A Z-test is a statistical test that is used to determine whether two population means are significantly different from each other. The Z-test is also known as the Standard Normal Test, and is used when the population variance is known.

What are the assumptions of t-test? There are several assumptions that must be met in order for the t-test to be valid. First, the data must be normally distributed. Second, the variances of the two groups must be equal. Third, the two groups must be independent of each other. Finally, the observations must be independent of each other.

How do you use the t-test formula? There are a few different ways to use the t-test formula, depending on the type of data you have and the question you are trying to answer.

If you have a population of data points and want to know whether the population mean is significantly different from a known value (such as 0), you can use a one-sample t-test.

If you have two independent samples of data and want to know whether the means of the two populations are significantly different, you can use a two-sample t-test.

If you have paired data (such as before-and-after measurements on the same individuals) and want to know whether the means of the two related populations are significantly different, you can use a paired t-test.

##### How do you find the t-test statistic?

There are a few different ways to calculate the t-test statistic, but the most common method is to use a t-table. To use a t-table, you first need to know the degrees of freedom, which is the number of data points minus the number of parameters being estimated. For a two-tailed t-test, the degrees of freedom is equal to the number of data points minus two. Once you have the degrees of freedom, you can look up the t-statistic in a t-table, which will give you the probability that the null hypothesis is true.