• Unit 8: Hypothesis Testing

A student competing in the science fair performs an experiment on the growth of tomato plants. She applies fertilizer to one group of tomato plants and no fertilizer to another group. At the end of the experiment, she weighs all of the tomatoes grown in each group. The fertilizer group averages 5.2 pounds per tomato plant, and the nonfertilizer group averages 4.9 pounds per tomato plant.

It is obvious that the fertilizer group has produced a higher mean yield, but is it just slightly higher or significantly higher? Could the difference in the two yields be attributed to just chance, or did the use of the fertilizer make a real difference? Could the fertilizer company use these results to claim that their fertilizer will definitely contribute to a higher plant yield?

This is an example of the type of experimental situation that you will encounter in analyzing data and using the results to make an inference about an entire population.

In previous units you learned about probability, sampling, experimental design, and various statistical distributions. In Unit 8, you will put all of this information together. You will perform actual statistical tests of hypotheses and make decisions based on the experimental outcomes. You will be using the same analysis techniques and tools that professional researchers use on a daily basis. This unit is the culmination of all previous units, and its mastery will stand you in good stead for research you might conduct in the future.

Completing this unit should take you approximately 11 hours.