Understanding Significance (chapter 4 in text; pp. 87-110 in supp.)
The purpose of this unit is to understand interpretations on determining if any changes occurred as a result of an intervention.
The following objectives will be covered in this unit:
1. What does significance mean?
2. How is significance related to probability?
3. What is the null hypothesis?
4. Why would we need to use a t-test?
5. What is an Independent Variable?
6. What is a Dependent Variable?
Consider the following problem: suppose a physical education teacher wanted to know if a ten minute verbal lesson in basketball shooting techniques would have any effect on shooting ability of general physical education class students. Let the population for this study be all of the male physical education students at a given high school. The teacher (investigator) randomly selected one hundred subjects from a list of all students enrolled in the school, He then contacted the selected subjects and made appointments with each one to meet him in the gymnasium dressed for activity. One group was randomly selected to serve as the control group while the other group served as the experimental group. The control group received the following: a ten minute verbal lesson on zone and man to man defenses, a five minute warm-up, and then each subject was tested on their shooting performance by taking 20 free throws. The experimental group received the following: a ten minute verbal lesson on basketball shooting techniques, five minute warm-up, and then each subject was tested on their shooting performance by taking 20 free throws. The following data was collected:
Control Group Experimental Group
N= 50 N=50
mean= 9.5 mean= 11.3
SD= 2.7 SD=3.2
What is the investigator interested in studying?
What is the IV and DV?
How would we apply the null hypothesis in this example?