WEEK 4 DQ2 MAIN POST DUE FRIDAYDescribe the levels of evidence and provide an example of the type of practice change that could result from each.Different levels of evidence exist and they are helpful in coming up with clinical decisions. The levels of evidence were originally illustrated in the report on periodic health examination in 1979 (Burns, Rohrich, & Chung, 2011). That is when a system of rating evidence was developed. Randomized clinical trials were described as the highest level of evidence since they are unbiased and less likely to result to systemic error. This is because there is randomizing of confounding factors which bias the results. According to this report case series and expert opinion were considered as the lowest levels because of their high probability of being biased based on author experience and lacks control of confounding factors.Over time, these levels have been transformed based on the working environment.