##### Asked by: Conchi Greenway

asked in category: General Last Updated: 20th June, 2020# How do you know if variances are equal?

**If**the

**variances are equal**, the ratio of the

**variances**will

**equal**1. For example,

**if**you had two data sets with a sample 1 (

**variance**of 10) and a sample 2 (

**variance**of 10), the ratio would be 10/10 = 1. You always test that the population

**variances are equal when**running an F Test.

In this regard, what does it mean when variances are equal?

'**variances equal**' simply **means** that the population **variance** for one thing is the same as the population **variance** for some other thing or things.

Also, what is T test used for? A **t**-**test** is a type of inferential statistic **used to** determine if there is a significant difference between the means of two groups, which may be related in certain features. A **t**-**test** is **used as** a hypothesis **testing** tool, which allows **testing** of an assumption applicable to a population.

Regarding this, when can we assume equal population variances?

Two sample standard deviations are very similar so **we will assume equal population variances**. 95% confidence interval contains 0 so cannot rule out that the **population** means may **be equal**. If sample sizes are **equal**, the pooled and unpooled standard errors are **equal**.

What is a paired t test?

The **paired** sample **t**-**test**, sometimes called the dependent sample **t**-**test**, is a statistical procedure used to determine whether the mean difference between two sets of observations is zero. In a **paired** sample **t**-**test**, each subject or entity is measured twice, resulting in pairs of observations.