Reviewing Chapter 3 for EC

Matched Pair Design One person tests two treatments, one after the other. The treatments being tested are ordered randomly.

You want to test two pair of running shoes You want to test two pair of running shoes. It just so happens that your track star friend’s favorite pair is one of them (Brand X). The other is a new brand (Brand Y). You flip a coin. If it lands on heads, your friend wears Brand X first and you will time her as she goes around the track; if it lands on tails, she wears Brand Y. You time her. After she has gone around the track once with the first pair of shoes, she goes around it again, but with the other pair of shoes this time. You time her again.

Variables link everything together… Lurking Variables are explanatory variables which may have caused the response variable, but they weren’t what you were testing. They are also known as “extraneous variables”…think of it as “extra” variables. If you don’t know if it was the lurking variable or the explanatory variable which caused the response variable, you have just experienced “confounding” Explanatory Variable Response Variable Lurking Variable

For your Taste Tests… Remember to keep everything the same if you have to do the taste test in multiple sittings. Otherwise you may have just created additional lurking variables. If this happens, just remember to address them in your write ups. Remember to randomize for everyone who is a taste tester. Don’t give everyone sample A first, unless that’s the way it worked out (the coin flipped the same way every time). Remember to have fun with it.