Is This Study Internally And Externally Valid?

Ask yourself is this study internally valid (do you accept the findings from the study?) and is it externally valid (can I apply this to my own patients?).

Internally validity is a judgement call on whether you think this review has achieved valid (true) conclusions. You can only apply the evidence from a review to your patients if you trust the results.

External validity or ‘generalisibility’ is another judgement call that you make after you have decided that you accept the result. This asks are the patients in this study like mine and should I use this treatment for them?