Constructing Graphs

Type of Graph. To determine the correct type of graph for your data ask this question:

DOES THE DATA BETWEEN INTERVALS HAVE MEANING?

If the data can be collected in between (both sets of data are measured with a piece of equipment) - LINE GRAPH

I the BAR GRAPH

Creating your Line Graph.

1. Draw and label the Axes:

· The x-axis is the manipulated variable.

· The y-axis is the responding variable.

· Your origin should always be 0,0.

2. Determine the Scales for Axes:

· Count the number of squares you have to work with.

· Take your highest value of data and round it to the next unit of 5.

· Take your number of the highest data and divide it 5. 5 is somewhat arbitrary, but it is usually results in an appropriate number of intervals.

· Round this number to a number that is easy to work with (2,5,10).

Example:

Highest data point is 31, round to 35. 35 ¸ 5 = 7. Round to 5. The scale should go by 5’s to get evenly spaced data in your graph.

3. Plotting your Data Points:

· Your value for the manipulated variable will be the x value (how many over).

· Your value for the responding variable will be the y value (how many up).

· An optional step that may help you keep track of your data pairs is to write them down in a chart.

4. Summarize Trends:

· Line of best fit. This type of graph is used when two sets of measurements are taken. When the line is drawn, you should have equal numbers of data points above and below the line.

· Connect the dots. This type of graph is used when the manipulated variable is a continuous measurement. Examples include time, days, months, years, etc.

5. Finishing Touches:

· Create a title for your graph.

· If you used any abbreviations, create a key to let the reader of the graph know what they mean.

Creating a Bar Graph.

· Draw and label the X-axis (manipulated variable) and Y-axis (responding variable.)

· Optional step: write your data pairs for the values of the two variables.

· Subdivide the X-axis to depict the discrete values of the manipulated variable. For example: each brand of paper towel or different people.

· Determine the appropriate scale for the Y-axis by following the steps listed in the Creating a Line Graph Instructions.

· Draw a vertical bar from the value of the manipulated variable (x-axis) to the corresponding value of the responding variable (y-axis). Leave spaces between each bar.