Give an example of a hypothesis and a null hypothesis. Explain the importance of each. Examples cannot be used by more than one student. Original posts need at least 100 words and response posts need at least 50.
For your response, explain what a Type 1 and Type 2 error would be for the student’s hypothesis.
Here are some examples:
A Type I error is rejecting a true null hypothesis, aka a “false positive.” This is accepting the experimental hypothesis when the null hypothesis is true.
A type II error is not rejecting a false null hypothesis, aka a “false negative.” This is rejecting the experimental hypothesis when the null hypothesis is false.
Example 1: Experimental research
You design a study to test whether or not eating a vegan diet high in spinach, decreases blood pressure.
Null hypothesis is that eating a vegan diet high in spinach does not affect blood pressure at all.
Scenario 1: The null hypothesis is actually true, but your study shows an effect so you reject the null hypothesis. (type I error, aka false positive, everyone will now eat lots of spinach but still have HBP)
Scenario 2: The null hypothesis is actually false, but your study shows no effect and you do not reject the null hypothesis. (type II error, aka false negative, you are depriving folks of a low cost cure for high blood pressure!)
Scenario 3: The null hypothesis is actually false, and your study shows an effect. You correctly reject the null hypothesis. No type I or type II error, and everyone with high blood pressure adopts a vegan diet high in spinach!
Example 2: Criminal justice system
Null hypothesis: innocent until proven guilty
Scenario 1: you are convicted of theft, but you are actually innocent. The jury rejects the null hypothesis when it is true (type I error), you are falsely incarcerated.
Scenario 2: you are acquitted of all charges, but you are actually guilty. The jury does not reject (accepts) the null hypothesis when it is false (type II error), you get away with the crime!
Scenario 3: you are acquitted of all charges, and you are actually innocent. The jury correctly does not reject (accepts) the null hypothesis. No type I or type II error, you are free to go and your record is expunged!
The system is supposedly setup to minimize type I errors.
