Depending upon the purpose of the assignment, research can be used to accomplish many things.
Whether you are writing to inform, persuade, or critique, research should be used in conjunction with your own ideas to support your thesis and your purpose. Do not let the research speak for itself. You, the writer of the document, are the most important voice. You are using outside sources to support your thesis. Therefore, let your comments, connections, objections, etc. play the strongest role in your paper. When you quote or paraphrase an outside source, always bring the paper back to your thoughts.
It is essential to use outside sources that are going to back up your argument. In many cases, researching will reveal evidence that might relate to the topic but does not support your side of the argument. Many assignments will ask you to acknowledge the other side of the argument, so be sure to research your topic thoroughly and from many angles.
For some assignments, outside research may not be necessary. Thus, in determining the necessary amount of research needed, first evaluate the topic of the assignment. For example, a paper that is based solely on one’s opinion will likely require much less research than one that covers a highly scientific subject. To be sure, always ask your instructor for specific instructions.