Civil Engineering Reference
In-Depth Information
Step 2. Decide if word is on page
Step 3. If word is on page, return with goal accomplished
Step 4. If word is not on page, scroll to next page
Step 5. Go to 2
Method B works well for a one page document if the word is easy to find. Some words
stand out and are easy to find. A word in caps, such as “GOMS,” looks different and is
very easy to find. We can quickly scan one entire page. But to search for the word
“method” one may have to scan a paragraph at a time. This will add to the number of
steps, and the method of scrolling and visual scanning will no longer be a good option.
A typical GOMS model describes user tasks and user knowledge in the form of
production rules. These rules can be tedious and time-consuming to formulate,
particularly when the tasks are complex.
GOMS itself does not identify the user goals. The user must identify the goals. There
are several traditional methods available for doing this: task analysis, interviews with
users, observation of users using similar systems, or intuition on the part of the analyst
(Kieras, 1998). There are always several ways to decompose a task and write a GOMS
program. The analyst must judge how users view their task, what their goals are, how
they decompose the task into subtask, and what steps the user will select to accomplish
his methods (Kieras, 1998).
Predicting Human Performance through GOMS
The results of a GOMS analysis may be used to predict human learning. The logic behind
it is that the greater the number of statements (steps), the longer the learning time. Kieras
(1998) noted that for a program with about 100 statements the learning time (LT) is as
follows:
LT=30-60 minutes+
N
×0.5 minutes
where
N
is number of statement.
As an example, Gray (1998) calculated the learning time for a computer game. He
showed that even ten-year-old boys take as long as their parents would take. The main
difference is that some boys have endless motivation. Parents are usually not aware of
how long a time their children spend to perfect a game, and therefore they elevate them to
the status of computer genius. Unfortunately this is rarely the case.
USABILITY TESTING
Usability testing has been established for more than 25 years. It is focused on identifying
usability problems in a product. The test is performed by a participant in a usability
laboratory. There are several characteristics of a usability test.
1. The focus is on usability
2. Participants are end users or potential users
3. Participants may be asked to think aloud as they do the task (see below)
4. Data are recorded and analyzed
