During the interview with the user, you should have a focus or purpose for a given interview and observation session. A focus is the number of assumptions and beliefs concerning the tasks to be accomplished in the session and how to go about reaching those goals. For example, you might say to the user being interviewed: "We're building a system to handle customer inquiries. This is a straight-forward process. This system should manage 100 customer inquiries a day." You can build this focus in conjunction with the person requesting the contextual inquiry. You can also build a focus by using focus groups or user surveys. Be aware that your focus is rarely 100% complete and accurate. There is always a percentage of missing or unknown assumptions that represent a part of the truth. For successful interview results, the interviewer should severely challenge the focus, based on data and observations in each session.