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Changes to This Summary (05 / 17 / 2012)

    The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

    Images were added to this summary.

    Recommended Related to Cancer

    Study Design Categories, Definitions, and Levels of Evidence

    Prospective, randomized, controlled trials and meta-analyses of prospective, randomized, controlled trials. The randomized, double-blinded, controlled trial is the gold standard of study design. To achieve this ranking, the study allocation must be blinded to the investigator both before and after the randomization and the assignment to intervention group. This design provides protection from allocation bias by the investigator and from bias in the assessment of outcomes by both the...

    Read the Study Design Categories, Definitions, and Levels of Evidence article > >

      This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

      WebMD Public Information from the National Cancer Institute

      Last Updated: February 25, 2014
      This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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