Graphs

Purpose Of a Graph Data collected in an experiment is often presented in the form of a graph. It is easier to interpret a graph than to read text or look at a table because a graph gives you a concise picture of your data. There are many types of graphs. This presentation introduces you to three: line graph, bar graph, and pie graph, and will help you decide which graph is the most appropriate for your data.

Types of Graphs Bar - Pie/Circle - Line -

Bar

Line

Pie/Circle

Which Graph to Use? Line graphs- show changes in a chosen variable; generally it is used if you are measuring a dependent variable and an independent variable. Bar Graphs – are used for data that represents separate groups or categories showing the differences between the groups. Pie Graphs – are used to represent part-to-whole relationships.

Constructing a Line Graph Identify the variable. Determine the scale for the X and y axis. Number each scale. Title each scale (include the unit of measure when ever possible). Plot the points of your data. Determine if the points will be connected. Title your graph.

Determine the scale for the X and Y axis The numbers used for the x and y axis must be the same distance apart. Example 1,2,3,4,5, or .5, 1, 1.5, 2, 2.5 100, 200, 300, 400 The scale does not have to be the same for the x and y axis.

The scale used will depend on the measurements taken. Example: Numbers taken- .75, 1.2 , 2, 3, 3.9, 4.6 Scale – 0, .5 , 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 Numbers taken -150, 175, 205, 240, 300 Scale – 50, 100, 150, 200, 250, 300, 350

Number Each Axis (The units do not have to be the same) 10 20 30 40 50 60 0 1 2 3 4 5 6 7 8 9 10 11

Title Each Axis (include the unit of measure when ever possible) 10 20 30 40 50 60 Time in seconds 0 1 2 3 4 5 6 7 8 9 10 11 kgm

Plot the Points of Your Data Time in seconds 10 20 30 40 50 60 0 1 2 3 4 5 6 7 8 9 10 11 kgm

Determine if the points will be connected Determine if the points will be connected. Connect the points, if there is information happening between the points. (Sometimes points are connected to make it visually easier to read your are not suppose to do this.) Time in seconds 10 20 30 40 50 60 0 1 2 3 4 5 6 7 8 9 10 11 kgm

Title your graph Roller blades and Mass 10 20 30 40 50 60 Time in seconds 10 20 30 40 50 60 0 1 2 3 4 5 6 7 8 9 10 11 kgm