d) You must apply the GOMS-Keystroke method in order to evaluate the average time to complete an online purchase form (see image below). The interface works as follows: the user must enter his credit card number (to simplify always 8 characters) and his expiration date (five characters, for example "08/10". Once the two fields are filled , the user must press the Validate card button The average validation time is 2 seconds.

Then, the user must choose his type of delivery. In 70% of cases, users choose regular post, while in 30% of cases they use expedited post. In the latter case, the user must choose the delivery company. Once the delivery option has been chosen, the user must press the "ok and send" button in order to proceed with the purchase. Movements between the various components of the interface are made using the mouse, the tab key does not move to the next component. GOMS-Keystroke evaluation variables: Keying = 0.2 sec. Pointing = 1.1 sec. Homing = 0.4 sec. Mental processes = 1.35 sec.

Mthode de paiment Numro de carte : Date dexpiration : Livraison Poste normale Poste acclre