Scatterplots Please view this tutorial and answer the follow-up questions on loose leaf or graph paper to be handed in to your teacher.

Scatterplot Basics Scatterplots have an x and y axis that represent two sets of data They can be used to compare two sets of information or track trends over time You DO NOT connect the points in a scatterplot In previous graphs, we would often sort data to make graphing easier. You CAN NOT sort data in a scatterplot.

Making a Scatterplot The height information will go on the x-axis and armspan will go on the y-axis. NameHeightsArmspans John Sally164 Mary Bob Kevin Sam Jen148 Jared Betty Don Since we have two sets of information, draw both a horizontal and a vertical axis. (Disregard the names!)

Making a Scatterplot Making a window for a scatterplot is slightly different than making a window for other graphs because you need to worry about both the x and y axis. For the x-axis, look at your x values and go a little lower than your lowest for the minimum and a little higher than the highest for your maximum. For the y-axis, look at your y values and go a little lower than your lowest for the minimum and a little higher than the highest for your maximum.

Making a Scatterplot HeightsArmspans Height (in cm) Armspan (in cm) Choose your x min, xmax and xscl based on your height information. Choose your y min, ymax and yscl based on your armspan information. Don’t forget to label each axis! This is very important!

Making a Scatterplot Height (in cm) Armspan (in cm) HeightsArmspans Next, you’ll need to plot the points. Take our first pair of (height, armspan) values.

Making a Scatterplot Height (in cm) Armspan (in cm) HeightsArmspans Imagine that you draw a line up from 156 on the x-axis. Mark your point where the two lines meet. Imagine that you draw a line across from 154 on the y-axis.

Making a Scatterplot HeightsArmspans Height (in cm) Armspan (in cm) Now mark the rest of your points the same way.

Making a Scatterplot Height (in cm) Armspan (in cm) When using a scatterplot to make comparisons, sometimes it helps to make a y=x line. This will help you figure out if the x- values are greater than the y-values or vice versa.

Making a Scatterplot Height (in cm) Armspan (in cm) Make sure that the y=x line goes through coordinates that have the same value for x and y. Sometimes the line will go diagonally through the graph, other times it will not. It depends on your mins, maxs, and scales.

Making a Scatterplot Height (in cm) Armspan (in cm) Points that fall exactly on the line will have the same x- coordinate and y- coordinate. Points that are above the line have y values that are larger than their corresponding x values. Points that are below the line have x values that are larger than their corresponding y values. y > x y < x or x > y y = x

Making a Scatterplot Height (in cm) Armspan (in cm) Notice that we have two points that are exactly on the line. (148, 148) (164, 164) These points have values where x and y are equal.

Making a Scatterplot Height (in cm) Armspan (in cm) Are heights or armspans larger for this class? There are six values below the y=x line. This means that six students had heights greater than armspan. There is only one value above the y=x line which means only one student had an armspan that was greater than the height. Since there are more points below the line, the heights are typically larger than the armspans for this class.

Creating a Scatterplot on the Calculator 1.Enter your data into a list 2.2 nd Y= 3.Select Plot 1 then Highlight “On” and hit ENTER 4.Under Type select the first choice.

Creating a Scatterplot on the Calculator 5.Make sure that you identify your x information and y information in Xlist and Ylist. 6.Set your window. 7.Hit Graph.

Follow Up Questions Answer the following questions and hand them in to your teacher.

Follow Up Questions Team Bat Rank Pitch Rank Colorado115 Houston22 San Francisco37 Atlanta41 Chicago511 Philadelphia614 Cincinnati710 Milwaukee812 New York94 St. Louis108 Pittsburgh116 San Diego123 Los Angeles135 Montreal148 Florida1516 Arizona Construct a scatterplot of these data pairs. Explain what the graph tells you about the relation between the teams’ batting and pitching. 2.Draw the y = x line on the scatterplot. Explain the relationship between the teams’ batting and pitching by looking at the points shown above, on, or below that line.