How to Create a Plot Graph

A plot graph is a chart that displays a mathematical relationship between two sets of data. Plot graphs are composed of points and lines. The points represent the data, and the line is the line that best connects the points. In order to create a plot graph, make a data table, determine the dependent and independent variables, label the graph, determine the scale, fill in the data and draw the best fit line. By analyzing a plot graph, you can draw conclusions about your experiment.

Things You'll Need

• Pencil
• Paper
• Computer
• Graph Paper
• Ruler

Instructions

1. Make a data table. When you perform an experiment, a data table is where you typically collect the data. For example, you may be performing an experiment about the pH of water when hydrochloric acid is added to it. You can make two columns on a piece of paper. One column can be for the amount of hydrochloric acid added in milliliters, and the other column can be for the pH of the solution. You can also do this on a spreadsheet on the computer.

2. Determine your independent and dependent variables. The independent variable is the factor about the experiment that you change, and the dependent variable is the factor that changes based on the independent variable. For example, in your pH experiment, the amount of hydrochloric acid added is the independent variable, and the pH of the solution is the dependent variable.

3. Label the plot graph. The vertical, or y-axis, is where you write the independent variable. The horizontal, or x-axis, is where you write the dependent variable. You write the title of the graph at the top of the graph. For example, the y-axis of your graph is hydrochloric acid added (mL), the x-axis is pH of solution, and the title is "Amount of Hydrochloric Acid Added To Water vs. pH." If you do the plot graph online, first highlight the data table, then press chart, then select the type of plot that you want, and then label the graph.

4. Write or type the scale. The scale is displayed on the y-axis and x-axis of the graph. How you make the scales depends on the collected data. For example, if your range of milliliters of hydrochloric acid added to the water is from 0 mL- 100 mL, and you took the pH of the solution after the addition of acid in increments of ten milliliters, then you may want to make your scale in increments of 10. For the pH, your range may be from 1-7. Therefore, you can put your scale in increments of one.

5. Fill in the data. Using your data table, put the values on the plot graph. For example, at 0 mL of hydrochloric acid added to water, the water had a pH of 7.0. Find 0 mL on the x-axis of the graph, and find 7.0 on the y-axis of the graph. The intersection of these values is where you make your data point. Do this for all of the values.

6. Draw the best fit line. The best fit line is the line that shows the general relationship of the data. Place a ruler over the data points. Then, draw the line. If the plot graph is on the computer, you can right click one of the data points, and then click the option to add a trend line.

References

• The Free Dictionary: Graph
• Illinois: Scatter Plots
• North Caroline State University: Graphing with Excel