It's important to be critical of information you find online. When it comes to statistics and "facts," be sure you can identify the source and verify their validity. When it comes to social research, you can depend on government sites (sites ending in .gov) and most professional organizations (usually ending in .org). Educational institutions (ending in .edu) are usually reliable as well. When it comes to sites ending in .com, .net, and .biz, you should be cautious of how reliable the source is.
In all cases, ask yourself "Who wrote this, why did they write it, and where did they get their facts?"