Related Experiment Video
Updated: Aug 19, 2026

Improvement of a Closed Chest Porcine Myocardial Infarction Model by Standardization of Tissue and Blood Sampling Procedures
Published on: March 12, 2018
How high can a correlation coefficient be? Effects of limited reproducibility of common cardiological measures
D P Francis1, A J Coats, D G Gibson
1Department of Cardiology, Royal Brompton Hospital, London, UK. d.francis@rbh.nthames.nhs.uk
Abstract:
In clinical studies the linear correlation coefficient is commonly used to quantify the strength of the association between two variables, such as height and weight: the value of r indicates whether the relationship is a strong one. However, actual clinical data includes an underlying physical variable plus an inevitable measurement error component that represents the reproducibility of the test used. If test reproducibility is poor, then even if the underlying physical variables are perfectly correlated, the actual observed correlation coefficient cannot be one but must be somewhat less. We present a method for calculating the reduction in correlation coefficient due to limited reproducibility, and discuss its implications with respect to experimental design and interpretation.
More Related Videos
09:18Doppler Ultrasound-Based Leg Blood Flow Assessment During Single-Leg Knee-Extensor Exercise in an Uncontrolled Setting
Published on: December 15, 2023
05:51Assessing the Accuracy of Fitness Smartwatch Data for Cardiovascular and Physical Activity Monitoring: A Validation Study in Digital Health
Published on: February 21, 2025
Related Concept Videos
Regression Toward the Mean
Errors occurring during blood pressure monitoring
Several factors...
Coefficient of Correlation
If you suspect a linear relationship between x and y, then r can measure how strong the linear relationship is.
What the VALUE of r tells us:
The value of r is always between –1 and +1: –1 ≤ r ≤ 1.
The size of the correlation r indicates the strength of the linear...
Correlation between ECG and Cardiac Cycle
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
Variability: Analysis
The range is a simple measure of variability, indicating the difference between the highest and...
Blood Studies for Cardiovascular System II: CRP, Hcy, and Cardiac Natriuretic Peptide Markers
These markers indicate stress or strain on the heart muscle:
Natriuretic Peptides (BNP)
Cardiac myocytes produce these hormones in response to ventricular stretching...