The "Enhance M-H charts" option on the Run menu, also known as the "Make M-H charts" option, is used to get "Lertap 5 DIF plots". This screen snapshot is what will be seen when the "+More" drop-down option is clicked on, although "Enhance M-H charts" may be labeled as "Make M-H charts":
Once selected, the option will result in a "DIF plot" for each test item, similar to the one shown here:
The chart above, for I35, reflects an item that meets the ETS criteria for C (large). There's quite a range of scores where the Nat. group consistently out-performed the Ing. group. This is a picture which may well suggest the presence of 'DIF', differential item functioning.
The chart above, for item I1, reflects no DIF, ETS level A (neg.).
When this option is taken, a check is made to make sure that an IbreaksMH worksheet report, such as IbreaksMH1, is open. Such reports are mentioned in the previous topic.
Users are then asked to pick out the range of test scores over which the plots are to be made -- in this example, the range was 8 to 36.
As the option begins its work, it first makes a copy of the open IbreaksMH worksheet so that another score range may be used for more plots.
Note that there is a handy way to select all of the "Lertap 5 DIF plots" in a worksheet and carry them over to a Word document. While looking at an IbreaksMH worksheet, hold down the <Ctrl> key on the keyboard and at the same time press the G key. A "Go To" box such as the following should appear:
Click on "Special", the button seen at the lower left of the box.
Select the "Objects" circle (also known as a "button"), click OK, and all of the plots (known more generally as 'charts' in Excel) will be copied to the clipboard. They may then be pasted into a Word document. If there are tens of plots, when they are pasted page breaks will be correctly observed so that any single plot will not split over two pages.
For other pictures of DIF, see, for example, Figure 4.4 in Camilli & Shepard (1994), and FIGs. 3.1 and 3.3 in Dorans & Holland (1993). (Refer to: http://www.lertap5.com/References.htm.)