1. Scatter Plots and Equations of Lines

2. First the Data Data must be collected and organized.
For this example, you will be asked to write down some data about people you may know.
Use your best estimate, even if you do not know that person.
Decide quickly, and write it down.

3. How old are they, really?

4. Mick Jagger

5. Ashley Tisdale

6. Keanu Reeves

7. Angelina Jolie

8. Justin Timberlake

9. Cher

10. Jamie Foxx

11. Taylor Swift

12. Tony Hawk

13. Hillary Duff

14. Hugh Jackman

15. Drew Barrymore

16. George Clooney

17. Madonna

18. Tom Cruise

19. Jennifer Aniston

20. Johnny Depp

21. Julia Roberts

22. Jay Leno

23. Paula Abdul

24. Data Now what?
The ages you have estimated will serve as our input.
We will now reveal the true age (in 2011) of the celebrities you have just seen.
Write this actual age in the appropriate column on your data sheet. These will be our output.

25. Ready? Some of these may surprise you!
Celebrity Date of Birth Age in 2011
Mick Jagger July 26,
Ashley Tisdale July 2,
Keanu Reeves September 2,
Angelina Jolie June 4,
Justin Timberlake January 31,
Cher May 20,
Jamie Foxx December 13,
Taylor Swift December 13,
Tony Hawk May 12,
Hillary Duff September 28,

26. Celebrity Date of Birth Age in 2011
And . . .
Celebrity Date of Birth Age in 2011
Hugh Jackman October 12,
Drew Barrymore February 22,
George Clooney May 6,
Madonna August 16,
Tom Cruise July 3,
Jennifer Aniston February 11,
Johnny Depp June 9,
Julia Roberts October 28,
Jay Leno April 28,
Paula Abdul June 19,

27. The Scatter Plot
Follow these steps to create a scatter plot on your graphing calculator:
First Clear the RAM ( 2nd, + , 7 , 1 , 2 )
STAT, 1:Edit , then fill L1 with your estimates.
Now, fill L2 with the actual ages.

28. The Scatter Plot continued:
2nd , STAT PLOT , 1:Plot 1 , Enter ( to turn on)
ZOOM , 9:Zoom Stat
There’s your scatter plot! Sketch it neatly in a calculator window in your notebook.

29. The Line of Best Fit
Follow these steps to calculate the line of best fit on your graphing calculator:
2nd , 0 , “D” , scroll down until the arrow points to “Diagnostic On” , Enter , Enter.
STAT , CALC , 4 , VARS , Y-VARS , 1:Function , 1:Y1 , Enter
Write down your equation, rounding values to the nearest thousandth, if necessary.
Graph!

30. How did you do? Do you tend to estimate too high, or too low?
If you followed your equation to calculate your age, how old would you be?

31. Reflections:
A scatter plot is a graph of data points which shows the relationship (correlation) between the two values being measured.
A line of best fit is used as a best approximation of a summary of all the points in a scatter-plot. This line, or the equation of the graph of the line, can be used to make predictions about other possible outcomes.

32. Reflections:
The correlation coefficient is a measure of how well the predicted values, or estimates, "fit" with the real- life data.
The correlation coefficient (r2) is a number between 0 and 1.
If there is no relationship between the predicted values and the actual values, the correlation coefficient is very low .
A value of 0 would mean that the predicted values are no better than random numbers.
A perfect fit gives a coefficient of 1.0 and means that the output is 100% predictable by the input using the equation of the line of regression.