Learn It Part 2
Is there a possible correlation between the cost of a stamp and the years since email has been in use? What type of curve best fits the relationship between the price of gas and the years since the invention of the electric car? What equation works best to predict the depreciation of an automobile over the next few years? The following exercises will help you to learn how to perform a regression analysis on the variables in these situations and use the results to solve problems.
Residual Plots Tip
Use your graphing calculator to construct the residual plots. Residual plots that display a scatter of points equally above and below the horizontal axis, with no distinct pattern, signify that the regression curve is a good fit for the data.
Exercise 1: Is there a possible correlation between the cost of a stamp and the years since email has been in use?
The cost of the United States postage stamp has risen over the years, especially since the increased use of social media and email. The table below shows the cost of a stamp over the years. The data is graphed, and shown to the right of the table.
| Year | Cost (cents, ยข) |
|---|---|
| 1971 | 8 |
| 1974 | 10 |
| 1975 | 13 |
| 1978 | 15 |
| 1981 | 20 |
| 1985 | 22 |
| 1988 | 25 |
| 1991 | 29 |
| 1994 | 32 |
| 1997 | 33 |
| 1999 | 34 |
| 2002 | 37 |
| 2004 | 39 |
| 2006 | 41 |
| 2008 | 42 |
| 2009 | 44 |
| 2013 | 46 |
| 2014 | 49 |
Use the information above to answer the questions in the following activity.
Now go to the next page to continue practicing how to perform a regression analysis on the variables in different situations.
