The study type is key for assessing the importance and potential impact of research. ... Such studies fall into the category of epidemiological research, which aims to understand the causes, or risk ...

Other epidemiological studies of viral infections followed suit — hepatitis B and C viruses were identified as a cause of hepato-cellular cancer, and human lymphotropic virus type 1 was found to ...

1. Bortz J, Döring N: Forschungsmethoden und Evaluation. Berlin, Heidelberg, New York: Springer 2002; 39–84. 2. Bortz J, Döring N: Forschungsmethoden und ...

The weakest type of epidemiological study is a cross-sectional study, which only provides a snapshot in time. A case-control study is better because it compares sick people to healthy ones who have ...

Although both types of studies have limitations, together they make a rather strong case. "[W]hen you do these types of epidemiological studies, you are not really controlling for confounding ...

Study Type; No. of cases, including milder ones: ... More generally, it is useful to synthesize data from simultaneous surveillance studies, epidemiologic field investigations, ...