Which Type of Research Study Is Right for You?

Most of what we know about cancer comes from the results of research studies. Understanding what makes for a good study is important if you're considering a new treatment option or deciding whether you should participate in a clinical trial.

Research studies can be classified by type—observational or experimental—or time period. Prospective studies answer the question, "What will happen in the future?" Retrospective studies analyze what happened in the past. In observational studies, researchers simply observe and record naturally occurring events. Experimental studies evaluate what happens when people do something (for example, take a new drug). This is called an intervention. There are numerous subcategories of these study types and some are better for providing reliable and clinically relevant results.

Clinical trials are the most common type of experimental study. Unlike laboratory research, clinical trials involve people. Clinical trials advance through stages (I to IV) as long as the results continue to demonstrate the potential benefits outweigh the potential harms and risks. Clinical trials must adhere to strict safety and ethical protocols.

The gold standard for clinical trials and experimental research studies is the double blind, randomized control trial. Let's break this down into its components.

Double blind. Neither the researcher nor the participants know who is receiving the intervention (e.g. treatment) or control (e.g. placebo). This helps eliminate bias that might influence how researchers interpret results or participants respond to the intervention.

Controlled. These studies allow comparisons between a control group (those who don't get the intervention) and an investigational group, who does. It answers the question, "Compared to what?" Without a control group, scientists don't know if what they observe is caused by the intervention, by chance, or because of unknown factors.

Randomized. Study participants are randomly assigned to the control or experimental group. Random allocation ensures that all (or most) known and unknown confounding factors (those things that might influence the results) are evenly distributed between the two groups so they don't skew the results.

CancerNet suggests asking these questions to help you evaluate the quality of research studies.

  • Does the journal that published the study require peers who are not involved in the study to review the study methods and results?
  • How long is the study and how many people were involved?
  • Do the results support or contradict information already available?
  • Does the study overstate the results? Remember, individual studies are usually only part of the puzzle.




National Cancer Institute. "Which Study Results Are the Most Helpful in Making Cancer Care Decisions?" Web. 12 June 2003. http://www.cancer.gov/clinicaltrials/learningabout/goldstandard

Bionity. "Randomized controlled trial." Web.

Cancer.net. "Understanding Cancer Research Studies, Part II." Web. 10 November 2010.

Cancer.net. "Medical News: How to Know If It's Accurate?" Web. 7 April 2011. http://www.cancer.net/patient/All+About+Cancer/Cancer.Net+Feature+Articles/

Röhrig, Bernd, du Prel, Jean-Baptist, Wachtlin, Daniel, and Blettner, Maria. Prof. Dr. "Types of Study in Medical Research: Part 3 of a Series on Evaluation of Scientific Publications." Deutsches Arzteblatt International 106(15) (2009): 262-268. Web. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689572/

Gereige, Rani, M.D., MPH, FAAP. "Types of Research Studies: Architecture of Clinical Research." Powerpoint. University of South Florida. 15 August 2007. Web.