What are the possible disadvantages of using an online questionnaire sent to students’ university email address?

Thomas is a part-time master’s student who has been successfully self-employed for the last six years in the web technologies industry. As a consequence of his current employment status and area of expertise, he has chosen to research the impact of enterprise modules on undergraduate students at his university.
He is interested in seeing whether there has been an increase over the past 10 years in students considering selfemployment after their studies, particularly in the high-technology industries. Furthermore, as he is an expert in technology he wishes to put his skills to use in obtaining his data.
Thomas began his research project with a comprehensive search and review of the literature.
He broke down his search into three main areas: research methods, enterprise education and technologically oriented students. Following his review of the literature on research methods, Thomas felt his world view was most closely related to an objectivist paradigm within a positivist philosophy. Thomas used his review of enterprise education literature to develop his research aims and form four hypotheses to test. These were:
H1: Students’ desires to enter self-employment following graduation are greater compared with 10 years ago H2: More female students are considering self-employment following graduation compared with 10 years ago H3: More students wish become self-employed in the technology industry following graduation compared with 10 years ago H4: Students who take at least one enterprise module are more likely to wish to enter selfemployment following graduation than those who do not