How to Construct a Graph Use graph paper and a ruler to plot the values accurately. If using a database program, you should first sketch your axes and data points before constructing the figure on the computer. The independent variable is graphed on the x -axis and the dependent variable on the y–axis. The numerical range for each axis should be appropriate for the data being plotted. Generally, begin both axes of the graph at zero. Then choose your intervals and range to maximize the use of the graph space. Choose intervals that are logically spaced and therefore will allow easy interpretation of the graph, for example, intervals of 5s or 10s. Label the axes to indicate the variable and the units of measurement. Include a key if colors or shading is used to indicate different aspects of the experiment.
30 Choose the type of graph that best presents your data. Line graphsand bar graphsare most frequently used. The choice of graph type depends on the nature of the variable being graphed. Figures should be numbered consecutively throughout a lab report or a scientific paper. A figure legendshould be provided below each figure. This caption should start with the figure number followed by the title for the figure (concise and specific) and a short description of the figure. This description should include a short outline of how the procedure was performed and an explanation of any features illustrated in the graph. The caption should provide enough information to allow the figure to be self-contained. Capitalize only the first word in a figure title and place a period at the end. Any graphs you construct as part of you lab reports or as part of your homework should be constructed using computer software – handwritten graphs will not be accepted. The Line Graph Line graphs show changes in the quantity of the chosen variable and emphasize the rise and fall of the values over their range. Line graphs are used to present continuous quantitative data. For example, changes in a dependent variable such as changes in weight measured over time would be depicted best in a line graph. Whether to connect the dots or draw a best-fit curve depends on the type of data and how they were collected. To show trends, draw smooth curves or straight lines to fit the values plotted for any one data set. Connect the points dot to dot when emphasizing meaningful changes in values on the x -axis. If more than one set of data is presented on a graph, use different colors or symbols and provide a key or legend to indicate which set is which. A boxed graph, instead of one with only two sides, makes it easier to see the values on the right side of the graph.