Graphing Techniques (from BSCS Biology, A Human Approach Appendix b): Part A: Line Graphs 1. Review the data in the attached figure. Before you can make a graph using data you have collected, you need to organize your data into a data table. For this practice in graphing you will use this data. Number of Mice Caught in a Field Day Number of Mice Caught per 100 traps per night 0 25 30 45 60 38 90 30 120 20 150 14 180 13 210 8 240 7 270 11 300 4 330 13 2. Draw the x-axis and the y-axis for the graph. USE A RULER and graph paper so that your lines are straight and perpendicular. 3. Identify what information will go on the x-axis and what information will go on the y-axis. Information on the x-axis is usually constant in nature—for instance, items such as dates, numbers, miles, and sizes. Information on the y-axis is variable in nature—for instance, the number of mice caught, the number of people of a certain height, or the numbers of butterflies captured. 4. Label each axis of the graph using the headings of the data table. 5. Set up the number scales on each axis. Allow space on each axis for all the numbers that are included in the data table. (A number scale does not have to start with the number 1, but the numbers do need to be spaced in equal increments.) 6. Give your graph a descriptive title. 7. Plot the data on your graph by doing the following: a. Read one row of data from the data table, for example day 0 and 25 mice caught. b. Find the number on the x-axis where the piece of corresponding data fits (for example 0). c. Move up form the number on the x-axis to the place on the y-axis where the corresponding piece of data fits (for example, 25). d. Draw a dot, called a data point, at that place. e. Repeat steps a-d for all the pieces of data in the data table. 8. Draw a smooth line from left to right that connects the data points. This should help you see the relationship between the data points. Part B. Bar Graphs 1. Review the data in the following chart: Population of Heath Hens, Martha’s Vineyard, MA Year Population Size 1900 90 1905 45 1910 280 1915 1010 1920 55 1925 40 1930 10 2. Draw the x- and y-axes for the graph. 3. Decide which information goes on each axis. 4. Label each axis, using headings in the data table 5. Decide on the number scales or labels for each axis. Position the numbers on the x-axis so that you can draw bars in the spaces between the lines. Place the numbers on the vertical axis next to the lines so that you can end a bar between two numbers if necessary. (Intervals need to be constant) 6. Add a title to your graph. 7. Plot the data by following these steps: a. Read 1 row of data from the data table, for example, year 1900 and population size 90. b. Find the label for the corresponding piece of data on the x-axis of the graph, (for example, 1900). c. Move up the column above the label to the appropriate number for that piece of data on the y-axis (for example, 90). d. Draw a horizontal line at that number to make the top of the bar. e. Color in the bar from that line down to the x-axis. f. Repeat steps a-e for all the pieces of data in the data table.
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