11. The observational studies do not rule out other factors like genetics and diet. 12. This keeps the whole data collection process of the observational study entirely unobtrusive. 13. An Observational Study of Five Psychiatry Journals That Mandate Prospective Clinical Trial Registration 14. However, these findings were identified on the basis of epidemiologic observational studies alone. 15. Two meta-analyses of observational studies in sub-Saharan Africa were published in January 2015. 16. Hawk noted that this was an observational study , not a randomized, controlled trial. 17. Paired " t "-tests are a form of confounding factors in an observational study . 18. The problem, says Love, is the data come from observational studies , not random ones. 19. A few more recent reviews have also studied the results of non-randomized, observational studies . 20. Confounding by indication has been described as the most important limitation of observational studies .
