Hypothesis Testing Using a Null Model
Many students have difficulty with understanding the logic behind hypothesis testing. I’ve found that
requiring students to draw a clearly labeled null model while performing tests clarifies the entire
process. A null model is simply a model of the sampling distribution if the null hypothesis were true.
General steps:
1. State the null and alt hyp – (condish)
2. Draw a Null Model
3. Check your sample with the model. Could it have happened by random sampling variability?
Example one:
In 2000, 18% of ninth graders smoked cigarettes, has this changed? You collect a sample of 38 students
and find that only 5 smoke….. What can you conclude?
Suppose that in your sample 2 smoked… Would that be significant?
This is just a general introduction to Null Models. If used well, they really impact a students conceptual
understanding of hypothesis testing. Null models can be used for all of the tests that we run (Z and T).