# Misplaced Confidence in Observed Power

## TL;DR

This paper critiques the misuse of post-hoc power analysis in a clinical trial, emphasizing that such methods can be misleading and do not reliably assess the study's validity.

## Contribution

It highlights the fallacy of relying on observed power calculations after data collection to evaluate study results.

## Key findings

- Post-hoc power analyses are often misleading.
- Observed power does not reflect true study reliability.
- The paper advocates for proper interpretation of statistical results.

## Abstract

A recently published randomized controlled trial in JAMA investigated the impact of the selective serotonin reuptake inhibitor, escitalopram, on the risk of major adverse events (MACE). The authors estimated a hazard ratio (HR) of 0.69 (95% CI: 0.49, 0.96; $p$ = 0.03) and then attempted to calculate how much statistical power their study (test) had attained, and used this measure to assess how reliable their results were. Here, we discuss why this approach, along with other post-hoc power analyses, are highly misleading.