Một sẽ có thể bắt đầu hiểu sự khác biệt quan trọng, và do đó hạn chế, của mỗi thiết kế nghiên cứu, trường hợp một thiết kế có thể thích hợp hơn khác. Hãy ví dụ, sử dụng các tiếp xúc của năng lượng điện từ (EME) và kết quả bệnh ung thư (ví dụ như bệnh bạch cầu). | 26 . Glasser more appropriate when studies are used to detect rare or late consequences of interventions. Discussion One should now be able to begin to understand the key differences and therefore limitations of each study design and circumstances where one design might be preferable to another. Let s for example use the exposure of electromagnetic energy EME and cancer outcome . leukemia . With a cross-sectional study a population is identified target population cancer rates determined and exposure and lack of exposure to EME is ascertained in a sample. One then analyzes the exposure rates in subjects with cancer and those that are cancer free. If the cancer rate is higher in those who were exposed an association is implied. This would be a relatively inexpensive way to begin to look at the possible association of these variables but limitations should be obvious. For example since there is no temporality in this type of design and since biologically exposure to EME if it did cause cancer would likely have to occur over a long period of time one could easily miss an association. In summary it should be evident that observational studies . cross-sectional case-control and cohort studies have a major role in research. However despite their important role von Elm et al. discussed the lack of important information that was either missing or unclear in prior published observational studies and why this lack of information lead to a guideline document for reporting observational studies the STROBE statement - the Strengthening and Reporting of Observational Studies in Epidemiology . The STROBE statement was designed after the CONSORT - the Consolidated Standards of Reporting Trials - this statement outlines the guidelines for reporting RCTs. The STROBE statement is a checklist of 22 items that are to be considered essential for good reporting of observational References 1. Parker_Palmer. http wiki Parker_Palmer 2. Vickers AJ. Michael
