Hello, this is Claire Twose again. I'd like to introduce you to the section that covers searching principles. We're going to introduce you to the standards for doing a search, a high quality search that supports a systematic review. Among the things you're going to learn are the sources that you need to search, the electronic databases, how to structure the search, so it actually works in those databases and is recordable and reproducible. We're also going to introduce you to one of the key tenets of doing a systematic review, document your search. Document what you're doing. I'm going to be covering some of the evidence that's available on publication bias, on why you need to be doing this sophisticated search, when you're doing a systematic review. Dr. Kate Dickerson will introduce you to additional forms of bias and assessing the risk of bias in clinical trials. There are two ways that bias can get into your systematic review and meta-analysis. And that we're going to talk about in the middle part of this course. The first way is there can be bias in the individual studies that you include in your systematic review. And the second way is there can be a bias in the way that you do your systematic review and meta-analysis. We're going to talk about both. The first type we call a risk of bias, and we'll talk about that. Some of you may think about it in terms of the quality of the included studies. The second part which is bias in how you do your systematic review of meta-analysis, we refer to as metabias. And we're going to talk about that. In general, those ways have to do with publication bias, as Claire mentioned. That really relates more to metabias. In the individual studies, you can think of how the patients are allocated to the treatment they receive or the exposure that they get, how we collect the data. Those are different ways that bias can influence the individual studies that are included. Then one other aspect that we're going to include in this middle part of the course has to do with something called qualitative synthesis. This comes before you actually do the meta-analysis, or the quantitative synthesis. And the qualitative synthesis is arguably the most important part of the systematic review, and also difficult to sort of get your arms around and figure out what it is. It's a way of talking about the studies that you've included and what you've done. It's how the characteristics of the studies can influence the total view. It's how bias in the individual studies can influence your overall picture. And it's a qualitative putting together of all the individual studies that you have before you do a meta-analysis. So those are the aspects that I'm going to be talking about and that we'll bring into the course, about in the middle, before we get to the meta-analysis.