Data Analysis & Graphs

DATA ANALYSIS & GRAPHS
Graphs are often an excellent way to display your results. In fact, most good science fair projects have at least one graph.

• Review your data. Try to look at the results of your experiment with a critical eye. Ask yourself these questions:
  • Is it complete, or did you forget something?
  • Do you need to collect more data?
  • Did you make any mistakes?
• Calculate an average for the different trials of your experiment, if appropriate.
• Make sure to clearly label all tables and graphs. And, include the units of measurement (volts, inches, grams, etc.).
• Place your independent variable on the x-axis of your graph and the dependent variable on the y-axis.

For any type of graph:

• Generally, you should place your independent variable on the x-axis of your graph and the dependent variable on the y-axis.
• Be sure to label the axes of your graph— don't forget to include the units of measurement (grams, centimeters, liters, etc.).
• If you have more than one set of data, show each series in a different color or symbol and include a legend with clear labels.

Different types of graphs are appropriate for different experiments. These are just a few of the possible types of graphs:

A bar graph might be appropriate for comparing different trials or different experimental groups. It also may be a good choice if your independent variable is not numerical. (In Microsoft Excel, generate bar graphs by choosing chart types "Column" or "Bar.")

A time-series plot can be used if your dependent variable is numerical and your independent variable is time. (In Microsoft Excel, the "line graph" chart type generates a time series. By default, Excel simply puts a count on the x-axis. To generate a time series plot with your choice of x-axis units, make a separate data column that contains those units next to your dependent variable. Then choose the "XY (scatter)" chart type, with a sub-type that draws a line.)

An xy-line graph shows the relationship between your dependent and independent variables when both are numerical and the dependent variable is a function of the independent variable. (In Microsoft Excel, choose the "XY (scatter)" chart type, and then choose a sub-type that does draw a line.)

A scatter plot might be the proper graph if you're trying to show how two variables may be related to one another. (In Microsoft Excel, choose the "XY (scatter)" chart type, and then choose a sub-type that does not draw a line.)