Rules of thumb for critical appraisal:

the first rule in critical appraisal is to focus on how the data was collected and not on how it was analyzed

if the raw data or simple stats do not suggest an effect, then the effect found by sophisticated statistics is unlikely to be important in practice.

from: Michael Power, Clinical Knowledge Summaries Service www.cks.library.nhs.uk

• Critical Appraisal and Other EBM Worksheets Dartmouth College

Includes PICO (Clinical Question), critical appraisal, applying to patient, and CAT worksheets - in pdf and Word format.

• Critical Appraisal Worksheets Duke University

These worksheets are based on the JAMA articles. In Word and PDF.

• Expanded critical appraisal sheet (with explanations) for THERAPY. Duke Unviersity

• Evaluation of studies of treatment or prevention interventions. Evidence Based Nursing Oct 2000; 3:100-102.
  

Excellent explanation of the critical appraisal questions.

• A simple method for evaluating the clinical literature. Flaherty RRJ. Fam Pract Manag. 2004 May;11(5):47-52.

• Critical Appraisal of the Literature

Miser WF. J Am Board Fam Pract 12(4):315-333. Good article walking you through the EBM process with 2 cases. (Free from Medscape; requires registration)

• Consort statement The CONSORT Statement is intended to improve the reporting of a randomized controlled trial (RCT), enabling readers to understand a trial's design, conduct, analysis and interpretation, and to assess the validity of its results. It emphasizes that this can only be achieved through complete transparency from authors. This site provides lots of useful information explaining validity concepts.

• Study Design Concepts - http://academics.ashs.edu/faculty/mkronenfeld/EBM powerpoints/Study_designRCB.ppt A difficult challenge in teaching EBM to clinical students is teaching the methodological and statistical concepts needed to be able to read and understand research studies. This is especially true in clinical programs where the students are training to be clinicians, not researchers. Here is the link to the PowerPoint presentation developed by the biostatician who co-teaches EBM with me for our physician assistant students. (Submitted by Mike Kronenfeld;
  This presentation was developed by Dr. Curtis Bay for the Fall, 2006 EBM class for the Physician Assistant Program at the A.T. Still Univ. of the Health Sciences – Mesa Campus.)

See also -- Is this study valid?

See also -- What are the results? (statistics)