MRCEM Notes

EBM Definitions

Summary of evidence-based medicine (EBM) definitions

Intention-to-Treat (ITT) Analysis

  • ITT refers to analyzing study participants based on the group they were originally assigned, regardless of whether they completed the treatment or adhered to the protocol.
  • This preserves the benefits of randomization and prevents bias, reflecting real-world treatment effectiveness.

Blinding and Double Blinding
  • Blinding: Concealing treatment allocation from participants, researchers, or assessors to reduce bias.
  • Double Blinding: Both participants and researchers (or assessors) are unaware of treatment allocation, minimizing placebo effects and observer bias.

External Validity
  • Refers to how well the results of a study can be generalized to other populations, settings, or conditions beyond the study sample.
  • High external validity means findings are applicable to real-world clinical practice.

Internal Validity
  • The extent to which a study is well-designed and free from bias, ensuring that observed effects are due to the intervention rather than confounding factors.
  • High internal validity indicates strong causal inferences can be made.

Heterogeneity (of a Study)
  • Describes the degree of variation in study results, populations, interventions, or methodologies among included studies in a systematic review or meta-analysis.
  • High heterogeneity suggests variability that may limit the ability to pool study results meaningfully.

Homogeneity (of a Study)
  • The opposite of heterogeneity; indicates that study results, populations, interventions, or methodologies are similar across included studies.
  • High homogeneity strengthens the reliability of pooled data in meta-analyses.

P-Value
  • A statistical measure representing the probability that observed study results occurred by chance.
  • Specifically a p-value is defined as the probability of obtaining results as extreme as (or more extreme than) those observed in the study, assuming the null hypothesis is true.
  • Typically, a p-value <0.05 is considered statistically significant, suggesting that the observed difference is unlikely due to chance alone, and providing evidence against the null hypothesis.
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