Question

“A dentist wanted to determine which brand of toothpaste would make teeth whiter. He gave his patients Crest and Oral B.  The patients brushed for the same amount of time, used the same amount of toothpaste and had their teeth checked each week”

As you know experimental design has many concepts, from the example above please identify the:

1. Independent variables
2. Test unit
3. Dependent variables
4. Extraneous variables

Answer 1

Answer:

Independent variables are the one that are not dependent on happening of any of the other event. In the above case, the independent variables are the brand of toothpaste, amount of time for which the patient brushed and amount of toothpaste being used by them.

The test unit is the major entity that you are analyzing and testing in your study. In the above case, the test unit is the teeth of the patients.

Dependent variables are the one that are dependent on happening of independent variables. In the above case, dependent variable is the whitening of the teeth that is dependent on the independent variable mentioned above.

Extraneous variables are all variables, which are not the independent variable, but could affect the results of the experiment. In the above case, extraneous variable is checking of the teeth by patients for every week.