Graph Driven Tests

The Graph-Driven Test is a concept where DataClassroom uses the way data has been visualized to recommend an appropriate statistical test from this list:

• T-test
• Chi-square goodness of fit
• Chi-square test of independence
• ANOVA
• 2-way ANOVA
• Linear regression
• Advanced test modes (see here for details)

See this blog post for some pedagogical background, and the video below for a demonstration.

To perform Graph-Driven Test (GDT), first set up a graph that visualizes your data. Let's say you are comparing two groups of measurements, and you are showing them in a way that allows you to compare their means:

But you want to know: is the apparent difference in means statistically significant?

You can start the GDT from two places, the flowchart (Table tab):

Or from the Graph tab click on this button:

Performing the test

Clicking the button will open the GDT window:

You can see a list of tests, what DataClassroom expects to see on each axis in order to choose that test. One row has been highlighted and has a Calculate button which will start the test.

Test results

Once the test has run (only takes a second or two) you see the results:

There is a table of numerical results, in this case the Degrees of Freedom, the T-Score and the P-value. These will vary depending on the test, but there will always be a P-value as the final result.

The P-value is presented both numerically and with a suggested interpretation.

• Clicking the Explain... link takes you to a page which allows you to explore the meaning of the P-value in more detail.
• Clicking the Camera icon copies the table to your clipboard, ready for pasting into a spreadsheet or document.