The evaluation techniques shown in figure 8.1 Will provide the data needed for the a-t-a-r model. You are not yet acquainted with the various tests, but they will be tied into the a-t-a-r model as they come up. Though various evaluation events can help on several of the key factors, we are usually most interested in the one event that makes the biggest contribution - noted as best in the figure. And we should know which these are prior to starting the evaluation. That way, we spend our limited funds first on the best step and then on others if funds are available. Also, if we have to skip a step, we immediately know we are leaving open the question of whether users are likely to try the item when it be comes available. If we are going to do product use testing, then is should be set up in a way that lets us go through a concept test in the process of getting people to sign up for the use testing. It's later than we wanted, but better now than not at all.