Authentication is the process whereby respondents dialing in to your website to take a survey are validated before an interview begins. You define the validation that is to take place in the AuthenticateSampleRec function.

A simple scenario would be that the administrator sends to all of the prospective respondents an email containing an invitation to participate in the survey, an ID, and a password. Before starting the interview, each respondent must enter their ID and password on the authentication page. When the page is posted, UNICOM Intelligence Interviewer - Server calls the AuthenticateSampleRec function, which searches the sample table for a record with a matching ID and password. If a matching record is found, the respondent is authenticated and the respondent proceeds to the first page of the interview. If there is no matching record, UNICOM Intelligence Interviewer - Server displays the authentication-retry page so that the respondent can reenter their details. If the information cannot be authenticated after six attempts, the authentication-failed page is displayed. In this example, Id and Password are the authentication fields.

Prior to starting the project, the administrator has setup a quota for various characteristics--for example, 1000 men and 1000 women in three different age groups (18-24, 25-34, and 35-44). Respondents do not receive a personal invitation but find their way to the interview by following links on various popular websites. The authentication page asks each respondent to enter various personal details, including their age and gender. The AuthenticateSampleRec function checks the quota for these characteristics. Provided that the quota for the respondent's characteristics has not been filled, authentication succeeds, AuthenticateSampleRec creates a sample record, and the respondent proceeds to the first page of the interview. If the quota has been filled, the authentication fails and the interview-rejected page is displayed.