micheledpierri.com: statistics, data analysis and coding
Nexus of Statistics, Data analysis, Coding, Art and Medicine
The Anatomy of Suffering: Frida Kahlo through the Lens of Medical History Introduction: Why Frida Kahlo is the Patron Saint of Narrative Medicine In the intersection of art and clinical science, few figures loom as large as Frida Kahlo (1907–1954). While often celebrated for her surrealist aesthetics and her role in Mexican Modernism, Kahlo’s work…
How to Put a Turbo on Regression Models Bootstrap Validation and Cubic Splines for Medical Data A practical guide for data scientists and clinical researchers working with limited medical datasets Last updated: December 2025 Author: Michele D. Pierri Reading time: 15–20 minutes Introduction — Why regression often disappoints in medicine Regression models are still the…
A Complete Guide to Multiple Imputation for Missing Data: When, How, and Why Last updated: November 2025 Author: Michele D. Pierri Reading time: 15–20 minutes Glossary MCAR: Missing Completely At Random. Missingness is unrelated to observed or unobserved data; complete case can be unbiased. MAR: Missing At Random. Missingness depends only on observed variables; standard…
“Sickness, madness and death were the dark angels that had accompanied me since childhood.” Edvard Munch, Diaries, 1890 In the cold north of Europe, between the late nineteenth and early twentieth centuries, a Norwegian painter transformed his pain into vision. Not abstract pain, but one rooted in flesh, lungs, and nerves: a pain named tuberculosis,…
Introduction The softmax function is essential in mathematics and machine learning. It transforms a vector of real numbers into a probability distribution. Put simply, it converts a set of numbers into probabilities. To understand how it works, let’s look at a list of risk values for some patients: Patients Surgical Risk Patient A 2 Patient…
Introduction Decision Curve Analysis (DCA) is a powerful tool for evaluating the clinical utility of predictive models and diagnostic tests. Unlike traditional metrics like AUC or calibration, DCA focuses on what truly matters in practice: whether using a model leads to better decisions and outcomes. DCA was introduced by Vickers and Elkin in 2006 to…
Understanding DICOM Coordinate Systems and Image Orientation: Why Your 3D Volume Looks Upside Down 1. Introduction — Why Orientation Matters Have you ever opened a medical image and found the anatomy upside down or mirrored? It’s not your viewer’s fault — it’s about geometry. DICOM files contain not only pixels, but also the mathematical information…
Effect Size: What It Is and Why It Matters More Than Statistical Significance A result can be statistically significant — yet practically meaningless. Learn how effect size reveals the real-world impact of research findings. Introduction: The Hidden Problem with p-values You’ve probably seen headlines like: “New Study Shows Coffee Improves Memory!” But what if the…
Introduction The 2025 ESC/EACTS Guidelines on Valvular Heart Disease represent a pivotal shift in the balance between surgical and percutaneous interventions. While surgical aortic valve replacement (SAVR) remains the gold standard for younger, low-risk patients, the new guidelines expand the role of transcatheter aortic valve implantation (TAVI) and transcatheter edge-to-edge repair (TEER, MitraClip). This evolution…
Introduction: Understanding Calibration Challenges Consider a thermometer that perfectly identifies when one temperature is higher or lower than another, but consistently reads 5 degrees too high. This thermometer has good discrimination (it correctly ranks temperatures), but poor calibration (its absolute values are inaccurate). The same problem occurs with clinical risk models such as EuroSCORE: they…