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Internal and external validity are foundational to interpreting clinical research and applying evidence in practice. In this This Is Why lecture, Dr. Busti explains how validity is established, what threatens it, and how clinicians should evaluate it during critical appraisal.

This lecture is part of the This Is Why (TIW) evidence-based medicine series, helping clinicians connect study design to real-world decision-making.

Topics Covered:

- Internal validity vs external validity explained

- Independent vs dependent variables

- Causality in clinical research

- Threats to internal validity (history, maturation, testing, instrumentation)

- Statistical regression, selection, and mortality bias

- Threats to external validity (testing, selection, setting)

- Hawthorne effect and reactive behavior

- Multiple-treatment interference

- Applying evidence to patient care

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#internalvalidity #externalvalidity #biostatistics #studydesign #DrBusti

Disclaimer:

This content is for educational purposes only and is not medical advice. It does not replace individualized evaluation, diagnosis, or treatment. Always seek the advice of a qualified health provider with questions about a medical condition and never delay care because of educational content.