What Makes a Scientific Study "Good"?

Let's start with something easy. Check the date of the article. Typically, you'll want current research, but this comes with a few caveats. First, it depends on the topic. Some topics have had a lot of groundbreaking research come out over the past few years, while others haven't.

The other exception is a landmark paper, i.e., an influential paper. There's no exact number of how many times a paper needs to be cited for it to be considered a landmark paper, but if you're looking at something that's been cited hundreds of times, it likely made a big impact. Obviously, there is an exception to this exception. If someone makes a mistake, that paper will be cited quite a bit. For example, the Wakefield study linking vaccines and autism has been cited nearly 5,000 times, and it has also been retracted and debunked.

To see how many times your paper has been cited, look it up by title in Google Scholar and look for "Cited By":

Let's say your article is too dated. What now? You can find more recent research by looking up the paper in Google Scholar and checking its "Cited By" section. This is also a fantastic way to find out what other researchers think of the paper. To do this, look for a link that says "Cited by" and click it:

See if any of the newer papers look relevant, and use one of those. 

If the number of cited papers is too high to reasonably go through, click the Cited by.. link then check off the box that says "Search within citing articles":

Then, go back to the search bar and type in one word that describes what you're looking for to narrow the list. Then you can select from that list. And bonus: when you read the more current paper, since it cited the older paper, you'll get a little summary of what the other paper is about.

Now, some papers haven't been cited at all. That's not necessarily cause for concern, because it's pretty common. If that's the case, you can use Related Article suggestions in Google Scholar. Or, go to PubMed and look up the title. Not every paper is in PubMed, but most are, so it's worth it to check. Check the section called Similar Papers and see if you can find something newer.