Fit Graph of Items
This option produces a graphical mapping of weighted (infit) mean square values for each item.
- Select Reports - Item Reports – Fit Graph of Items from the main menu.
- You will be presented with a dialog window similar to the one shown in Figure 1. Enter an appropriate title and then a range of infit mean square values that are considered valid. Adams and Khoo suggest values between 0.75 and 1.33. Next, enter the range of mean squares to be plotted (values outside that range will be plotted on the relevant extreme edge of the range). Enter a calculation method of by parameter or by item and then select colors for the graph. The settings displayed in Figure 1 were used to produce the graph shown in Figure 2.
- As illustrated in Figure 2, the graph displays infit mean square values along the x-axis and item names along the y-axis. Points outside of the shaded area are associated with items exhibiting evidence of misfit.
- Select File – Save As PNG or File – Save As JPG. Each tab on the graph will be saved as a separate graphic file, using the name on the tab.
- Print the graphic using File – Print Select Chart.
- Close the window by clicking on the OK button.