# Two Sample t-Test Assuming Unequal Variances

## You can do t-Test in Excel using the Analysis Toolpak, but...

- Excel won't interpret your
*p-value*for you; the QI Macros will! - Excel can't give you a Box and Whisker chart of the two factors; the QI Macros can!

**How do you determine if the variances are equal or unequal?** Use an F-test to determine if the variances are *equal* or *unequal*.

If they are equal go to: Two-Sample t-Test assuming equal variances.

(The QI Macros Stat Wizard will do this for you automatically.)

### Video Example: Analyze Data Sets with a Two Sample t-Test

**Example of a Two Sample t-Test Assuming Unequal Variances**

In this example, we want to compare two types of structural steel and want to know if the strengths (in 1000 lbs/sq. in.) are the same or different. Next we conduct some tests and enter the data into Excel:

**Warning: **While you can run a t-Test using Excel's Data Analysis Toolpak, if you don't enter the two columns in the correct order, Excel will give you incorrect results. The QI Macros have eliminated this problem.

**How to Perform a t-Test Assuming Unequal Variances** using QI Macros for Excel

- Select the data with the mouse and click on the QI Macros Menu, Statistical Tools and then t-Test two sample assuming unequal variances:
- The QI Macros will prompt for a significance level (default is .05):

- Next the QI Macros will prompt for the hypothesized difference in the means (default is 0):

The QI Macros will perform the calculations and interpret the results for you:

**What's Unique About t-Test Calculations in the QI Macros?**

**What's Unique About t-Test Calculations in the QI Macros?**

When you run the t-test in Excel, the QI Macros will compare the p-value (0.197) to the significance level (0.05) and interpret the results for you. Cannot Reject the Null Hypothesis because p > 0.05" and that the "Means are the same".

### Learn More...

- t-Test one sample
- How to interpret Excel t-test results
- Paired two sample t-Test
- Two-Sample t-Test assuming equal variances
- Statistics Wizard analyzes your data and selects the right statistical tests for you

Hypothesis Testing Quick Reference Card