Table of Contents

• 1: Do those shoes fit?
• 2: Dilbert's 3 day work week
• 3: The day is saved ... or not
• 4: What you observe vs expect
• 5: The Chi-squared Equation
• 6: Give it a try
• Detour
• 7: What's a p-value?
• 8: What's a Lookup Table?
• 9: What's a "df"?
• Completing the Chi-squared Test
• 10: Interpreting a Chi-squared
• 11: The answer, finally
• 12: Summary
• 13: What about 90% M/F sick days?
• 14: What about 50% M/F sick days?
• Chi-squared in Biology
• 15: Testing for a dihybrid ratio
• 16: Review and Words of Wisdom

Learning Outcomes

After completing this module you should be able to:

• Explain how a chi-squared test  works and what it does
• Compute the test statistic for a chi-squared test
• Draw conclusions about two sets of data based on the information gleaned from using a chi-squared test.

Do those shoes fit?

In this module, we are going to discuss and explore a statistical test used for “goodness of fit”. What does this mean? You know whether your shoes fit your feet based on whether they cause pain, right?

In sort of the same way, you can decide whether your data fits your expectations using a “goodness of fit” test. And believe me, if your data doesn't fit, it can cause a lot of pain…

 

Note: having a calculator on hand will make things go faster. You can also use a spreadsheet, or calculator software on your computer, or google (to use google, type the numbers into the search bar, followed by an equal sign, and hit search).