Week 3 Discussion: Analyzing Correlation

This week, we are looking at the relationship between quantitative variables. We will concentrate on two variables for the purpose of this Discussion. We will be looking at the direction—positive or negative—and the strength—weak, moderate, or strong—of the correlation. There are no hard and fast rules on what numbers mean weak, moderate, or strong correlations; however, here is a rule of thumb:

0 < 0.4 weak
0.4 < 0.6 moderate
0.6 – 1 strong, where the numbers can be positive or negative.

Remember that you can only “prove” that one variable “causes” another by using an experiment. Be skeptical of observational studies that claim causation.

To prepare for this Discussion:

• Review the Week 3 Discussion resources.
• Look at the data set that you used in Discussion 1 and/or 2. In order to do this week’s Discussion, you will need to have two quantitative variables that you think might be related. In other words, changes in one variable result in changes in the other variable. If you do not have two variables like this in your data set, add another variable.

Example: I will go back to the original data set I used in the Week 1 Discussion. I think that a person’s weight is related to his or her systolic blood pressure. Since the systolic pressure depends on the weight, it will be the dependent variable in Statdisk, and the weight will be the independent variable. My data set is below.