If you are like many Internet users, you've jumped online at least once to look up physical symptoms you've been experiencing. Whether it's bloating, tingling or blurred vision, you've probably ran across at least one news article citing medical studies around the health condition you're researching. How do you know when a medical study is valid? Consider these four things when reading articles in the news and make sure the website you are visiting is a credible news or medical site.

Did The Study Involve People?

Research studies often start in labs and are tested on animals, but what works well in the lab and on animals doesn't always work well on people. Clinical trials are research studies that are safe and effective for people. These trials are conducted in a series of phases that build upon each other. Earlier phases find out if treatment is safe, if it works, or what its side effects are. Later phases test whether a treatment is better than what is already available.

How Many People Were Involved?

In general, the earlier phases of a clinical trial, the fewer people involved in testing. The most trustworthy scientific evidence comes later when there are hundreds or thousands of people. Some studies—case studies—are as small as one person. News stories about those people's success are interesting and exciting, but they don’t tell us much about the treatment and how it works in most people.

Does the Story Jump To Conclusions?               

Many studies are observational, looking for a link between a behavior and an outcome. For example, think about a study where people who drank red wine were less likely to die from heart disease. No one knows if the benefit came from the wine or something else the wine drinkers had in common. The only way to know for sure would be to conduct a randomized, controlled study where two groups of people were treated the same except for the one factor being studied.

Does the Story Add Up?

Numbers can be used to make a result more impressive than it really is. For example, a story saying a certain drug lowers your risk of stroke by 50%  sounds impressive, but the risk of stroke among the study population was only 2% and the drug lowered it to 1% - that’s less impressive. Also, if the drug is too expensive or has too many side effects for you, taking it might not be worth it.