Fundamental Features of Graphs All graphs have two, clearly-labeled axes that are drawn at a right angle. –The horizontal axis is the abscissa, or X-axis. –The vertical axis is the ordinate, or Y-axis. The independent variable is plotted on the X-axis, and the dependent variable is plotted on the Y-axis. The Y-axis must be a numerical scale. The length of the X- and Y- axis conforms to the ¾ rule. A graph contains only information related to the data and information that is necessary to interpret the graph.

Choosing Graphs Graphs are selected based on the scale and continuity of measurement. Scale of Measurement Continuity of MeasurementType of Graph ContinuousLine Graph Interval/RatioDiscontinuousHistogram Ordinal Bar Chart Nominal Bar Chart

The Bar Graph The Bar Graph : a form of graph that uses rectangles, or bars, to represent nominal categories. The bars do not touch. The nominal categories are plotted on the X-axis. The Y-axis of the bar chart may represent frequencies, percentages, or descriptive statistics such as the mean.

Histograms Histogram : a form of bar graph used to represent information when the X-scale is interval or better.

The Line Graph Line Graph : a form of graph in which a continuous line indicates the frequency or statistic presented along the Y-axis

Creating Graphs in SPSS In SPSS, you are given an option to create a graph any time you perform a statistical operation Click analyze in the menu bar. Scroll down to descriptive statistics and select frequencies from the pop out menu. In the frequencies dialog box, move the variable of interest to the variable window by highlighting it and clicking on the arrow. At the bottom of the window, click charts. In the charts dialog box, select the most appropriate graph for the data type. Click continue. In the frequencies dialog box, click OK. You can double click on the graph to edit titles, intervals, etc.

Reading SPSS Graphs

Creating Graphs in SPSS To create graphs in SPSS, you can go to graphs in the menu bar. Click graphs in the menu bar. Go to Legacy Dialogs. Scroll down to the most appropriate graph. In the chart dialog box, choose simple; summaries for groups of cases. Click Define. If you want to display the frequency of the variable, under bar/line represents, do nothing. If you want to display values of one variable as a function of another variable, check “other statistic”; the box underneath should light up. Select the dependent variable and move it to the variable box. Select the independent variable and move it to the category axis box. Click continue. Click OK.

Reading SPSS Graphs

Creating Graphs in Excel In all Excel graphs, Column A should include data for the X- axis. In all Excel graphs, Column B should include data for the Y- axis. Highlight the data (scroll the mouse over cells) you wish to use to create the chart. In the menu bar, click on insert and select the appropriate chart (if you want a bar chart, select column). After the graph is generated, click on it to make the chart tools available.

Creating Graphs in Excel Under chart tools, select layout. –Remove chart title. Click on chart title and select none. –Add axis titles. Click axis titles. Enter the titles for both the horizontal (X) and vertical (Y) axes. –Remove the horizontal gridlines. Click gridlines, horizontal gridlines, none. –Remove legend. Click legends and select none. –For bar charts, insert data labels. Select data labels. Choose inside end. Under chart tools, select format to change individual chart elements (e.g. bar color) or select design to choose from several preformatted styles and layouts. In the Excel spreadsheet, adjust the height and width of the graph to follow the ¾ rule.

Reading Excel Graphs