Unformatted text preview: Graphing in Microsoft Graphing in Microsoft Excel Type in the data using labeled columns. Click and drag to highlight the data you want to plot. If the data columns you want to plot are non sequential, hold down the Ctrl key while selecting each column separately. Click the button and select XY (Scatter) under “Chart Type”. Click Next. Click Next on the next screen. Give your chart a title and axis labels. DO NOT forget to include units on your axis labels. Do not click Next yet. Click on the Gridlines tab. Uncheck the box marked “Major Gridlines”. Do not click Next yet. Click on the Legend tab. Uncheck the box marked “Show Legend”. Click next. Click Finish on the next screen. Your chart should now be displayed. Adding Trendlines and Adding Trendlines and Pearson Correlations Right click on one of the blue data points. Select “Add trendline” in the drop down menu. Leave the Trend/ Regression type set on “Linear”. Click the Options tab. On the Options tab, select “Display R squared value on chart”. Click “Ok”. A trendline and an Rsquared value will now be displayed on your chart. Calculating Pearson Calculating Pearson Correlation Coefficient The Rsquared value shown on the chart is the square of the Pearson Correlation Coefficient. You must take the square root of that value to get the Pearson value, R. Remember to take into account the slope of the trendline. In the example case, the R value would be 0.9828 because the slope of the line is negative. When reporting correlations, remember to report the strength of the correlation. Use the following: |R|= 0.00 to 0.29 low |R|= 0.30 to 0.59 moderate |R|= 0.60 to 0.84 moderately high |R|= 0.85 to 1.00 high These are absolute values, so correlations of 0.92 and 0.92 would both be considered highly correlated. In order to calculate correlation in Excel without making a graph, use one of the following functions: =CORREL(columnA, columnB) =PEARSON(columnA, columnB) In the sample data set used for this tutorial, the function would look like this: =CORREL(A2:A11, B2:B11) When typing the function in the fx bar, do not forget the “=” sign. Choose another column to put your correlation in so you don’t get it mixed up with your other data. ...
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- Spring '09