Occurrence of cancer was identified between April 1991 and July 2000 for 50,000 troops who served the first gulf war (ended in April 1991). and troops who served elsewhere during the same period

Person's diagnosed with new - onset of Lyme disease were asked how often they walked through the woods, used insect repellent, wear short sleeves and pants, twice the number of patient without lyme disease from the same physician's practice were asked the same questions. results were from those with lyme disease and those without were then compared

Subjects were children enrolled in a health maintenance organization. at 2 months each child were randomly given one of the two types of vaccine against rotavirus infection. Parents were called by a nurse two weeks later and asked whether the children had experienced any list of side effects

Heath worker sampled residents of Pantal Dagupan City and asked of their food and lifestyle habit each month whether they have or had ever been diagnosed of hypertension