UPDATE provides an item summary, but it lists only the item number along with the mean RT and error rate for that item. ISUM does the same, but it also prints the actual item presented to the subject.
ISUM takes the item numbers for each condition specified in the DAT file, and then finds the items in the ITM file, and prints them. This means that ISUM presents you with a summary of the design of the experiment from DMASTR's point of view. If you have made an error in setting up the DAT file or the ITM file, then ISUM makes it easy to detect. For this reason, it is a good practice to run ISUM on each file before the experiment begins. Check that each of the items in each condition has been assigned to the correct condition.
Both the ITM and the DAT file must be available to ISUM. If necessary, change the default drive and directory to the drive and directory where your files are located. Then run the program by typing
isum <cr>
The program initially asks for a file name. Enter your file name without extension, e.g. EXP1
The program will ask you to choose one of three options, like this:
OUTPUT FORMAT:
(type appropriate letter)
(a) text only
(b) full item
(c) item listing (no RTs)
Option:
You should respond by typing the letter, a, b, or c, corresponding to the type of output you want.
If you select "b", the output for each item will show:
- the mean RT for the item,
- the percentage of incorrect responses for the item, and
- the full item, including correct reponse indicator, item number, text (characters between quotes) and special characters.
If you select "a", the correct response indicator, item number and special characters will be omitted.
If you select "c", the mean RT and percent incorrect responses will be omitted.
If you select "a" or "b", the program will also check your item file for such errors as duplicated item numbers and print a message if any such errors are found. If it finds any, check that this does not matter for your experiment. The only item numbers that should be repeated are for practice items and dummy items that you have no interest in. (Remember that if two items have the same number, only the RT from the last item presented will be stored.) The program will also tell you how many subjects have been incorporated in the DAT file, and print the mean RT for each condition.
To get a printed copy of the report which appears on the terminal, type Control-P before running ISUM and again after it has finished. Of course, this is only possible if there is a printer connected to the computer that you are using.
A disk file containing your ISUM output can be useful for the preparation of reports (the output file can be edited and rearranged like any text file). It is also useful if you are preparing a new experiment based on an old experiment. ISUM arranges the items by conditions, so it is possible for you to extract all the items in a particular condition from an old ITM file.
To get disk file output, you must re-direct output from the terminal to a specified file. This is done when you run the program by typing, for example,
isum >output.ism
Because all output now goes to OUTPUT.ISM and not to the terminal, you will not see any prompts. That means you have to remember what responses the program requires. They are the filename and the output option. You must enter them in the correct order.