(8-11)

For students to be able to analyze data to see what type, if any, correlation occurs.

A-5, AII-19

       This lesson is meant as a reference to illustrate various scatterplots to your students and what they mean. As the standarized testing becomes more analytical students need to have access to various scatterplots and their meaning.

       The first type of scatterplot will be a negative correlation. The picture should illustrate a decline in some form. I have used the temperature from July to Dec to show you a negative correlation. This could have been done with any of the data provided for you as long as their was a progressive decrease. It could also be explained with running. Hopefully, over time, your time running a certain distance decreases with increased practice.

To do a scatterplot on the TI82/83 calculator:

STAT

EDIT

(If there is already data in the lists, clear as follows: highlight, with the cursor, the L list that has data, push clear, then arrow down. The entire list will have been cleared.)

       Enter the months data (1 - 6) into the L1 list and the temperature data for those six months into L2. When finished, press Y=. This will take you to the stat plot menu. To insure that all plots are off; push 4. Plots off appears on the screen. Push enter again, and the word done appears on the screen. Now, all plots are off.

       Press Y= again to go to STAT PLOT.

Press #1. An entire new menu appears.

Make sure ON is highlighted.
Type: The first box is highlighted.
X-List is in L1.
Y-List is in L2.
Mark: the first one should be highlighted.

       Adjust your window/range to fit the data. Remember that the X-list are the monthes, so

X-min - 0
X-max - 7
x-Scl - 1
Y-min - slightly below the lowest number
Y-Max - slightly above the largest number
Y-Scl - 1

       Now, push Graph, and you should have a scatterplot that has a negative correlation.

Graph One

       The second type of scatterplot is a positive correlation. It shows an increase as time moves on. Here I am illustrating with the temperatures from the bay from Jan to July. You could explain this with going to the gym and over time being able to lift more weight if an example is needed that is not related to the bay. Remember to follow the steps above to be able to see a positive correlation.

Graph Two

       A linear correlation is one that resembles a straight line. Hopefully a line of regression is found after the scatterplot is discovered but that is another lesson. Follow the aforementioned directions for the following scatterplots.

Graph Three

       The last illustrated here will be a quadratic correlation. This could look like an upside down parabola. I am illiustrating with the temperature for a whole year from the bay. You will notice that they form a very natural curve.

Graph Four

       After showing your students the different scatterplots, they should have some sense of negative, positive, linear and quadratic.