TABLE 10 Experience in Developing Countries A. NUMBER OF COUNTRIES VISITED n = 179 Number Percent none 17.9 one 28.5 two-three 31.3 four + 20.7 B. DURATION OF STAY n = 179 Duration Percent < two weeks 21.8 two weeks - < six weeks 30.2 two months + 33.0 C. PRINCIPAL PURPOSE OF VISITS n = 179 Purpose Percent Research 43.0 Field Work 40.8 Conference Participation 33.0 Personal Visit 25.1 Teaching 17.9 Contract 14.0 Voluntary Work 7.3 Other .