Negative results are important, too . Don’t neglect the studies that don’t show anything. What do I mean? There is a bias towards positive results (., something happened or changed because of an intervention). Negative results are just as important because they still add to existing knowledge. Often people miss the data that doesn’t support the idea being put forward and authors choose to ignore that data, and instead put forward only that data that appeared to support their beliefs. If you read the research quoted deeper sometimes it contradicts the recommendations. Check to see that the information is complete, comprehensive, and verifiable through other resources.