The main factors influencing the cooperation in surveys over Internet, as suggested from empirical studies (Batagelj et al., 1998; Dillman et al., 1998), could be grouped into:
- factors influencing the contact with the respondent (e.g., awareness of the survey, e-mail solicitation plan);
- individual factors (e.g., socioeconomic characteristics, knowledge of the subject, experience with Web surveys) that shape the decision to participate as the result of the interaction of the individual characteristics of the respondent with the invitation of the survey designer.
When the survey is directed toward a specific target population with access to Web, often identified by an administrative file, there are many auxiliary variables available to understand the respondent behavior. In the case of the population of firms the list of the Chamber of Commerce is completed by the individual characteristics of the firm, such as the legal form, the number of employees, and the class of economic activity. The e-mail list does not represent the whole population of firms, it represents a segment with access to Internet that choose to publish the email address. Due to the development of the e-commerce, this segment in some sectors of economic activity covers a large part of the population and many firms in several sectors of economic activity are now joining the net to gain visibility. The diffusion of Internet has been growing in the small medium size enterprises, too. Although no complete coverage of the list is supposed, we work under the hypothesis that the list is our target population.