Hi everyone! Read through the material below, watch the videos, work on the Excel lecture and follow up with your instructor if you have questions.
- Collect, organize and graph raw data.
- Compute statistical parameters (covariance, correlation coefficient).
- Compute a regression equation and use it to make predictions.
Topic. This lesson covers: Covariance and Coefficient of Correlation
- Openstax Introductory Statistics:
- Introductory Statistics by Sheldon Ross, 3rd edition: Sections 2.5, 3.7
- Statistics with Microsoft Excel by Beverly J. Dretzke, 5th ed., COV(X,Y), CORREL(X,Y)
WeBWorK. Sets 12.2 and 12.3
The Applied View
Watch the video scatterplots.
- What is a manatee?
- What does a scatterplot show about the relationship between the number of powerboats registered in Florida and the number of manatees killed by powerboats?
- Why is the number of boats plotted on the horizontal axis of this scatterplot?
- What trend would you expect to see in a scatterplot of two variables that have a negative association?
Watch the video correlation.
- If it were true that two identical twins always had the same height, what would the scatterplot of the heights of several pairs of identical twins look like? What would be the correlation r between the heights?
- What are all the possible values of the correlation coefficient r?
- If heredity plays a strong role in determining personality, will the correlation between twins raised together be about the same as, or much larger than, the correlation between twins raised apart?
- Is it easy to guess how large the correlation is by looking at a scatterplot? Explain.
Use the Yahoo finance site to download a .csv file of historical data for your favorite public company. As an example, here are Tesla’s stock prices, however you may choose to investigate any company which catches your interest. Once you have your data, use Excel to:
|1) calculate the covariance of the two variables.|
|2) determine the coefficient of correlation r.|
|3) answer: What do these statistics tell you about the relationship between time and your company’s stock price?|