Internal vs. external validity

[Dr. Edd P.]

Can somebody share thoughts re the difference of INTERNAL VALIDITY and EXTERNAL VALIDITY? Can't find a decent source online regarding this topic. Thank you..

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[dempty]

I think it depends what you're talking about. Can you be more specific?

 

[Dr. Edd P.]

I think it depends what you're talking about. Can you be more specific?

Okay, like what's the best statement to think or just to have ready in case they ask it on the step, with regards to it's difference? and what are the factors that affect each? Thank you for taking time on this one..

 

[Dr. Edd P.]

Assuming you're talking about this in the context of statistics/research:

Internal validity has to do with how much the research study is vulnerable to bias due to methods. So for instance an uncontrolled drug trial with no blinding would have low internal validity; a double blind RCT would have high internal validity.

External validity has to do with how applicable the study results are to the general population. For example, in a study looking at management of HTN, if the participants have a relatively low rate of comorbid illnesses like DM or high cholesterol compared to the general population, the results might not be super applicable to other patients that do have more comorbidities.

Very informative thank you vvery much..