There is a bias in applied ML toward complexity. Gradient boosting, neural networks, and ensemble methods feel more serious than logistic regression. But for the kind of structured clinical data most health research produces, that complexity often adds noise without adding value.
The case for simplicity
Logistic regression has been used in clinical research for decades. It produces a probability estimate from a weighted combination of inputs, and every weight is visible. A clinician can look at the coefficients and check whether they make clinical sense. If age has a negative coefficient in a cancer recurrence model, something is wrong, and you can see it immediately.
With a gradient-boosted tree or a neural network, that kind of inspection is harder. Feature importance scores give a rough ranking, but they do not tell you the direction or magnitude of each variable's contribution in the same direct way.
The stability of logistic regression is underappreciated. Train a logistic regression model on ten different bootstrap samples from the same dataset and you will get similar coefficients each time. Train a gradient-boosted model on the same ten samples and the feature importances may shift substantially between runs. For clinical applications where consistency matters, where the model needs to give similar answers to similar patients, logistic regression's stability is a genuine advantage.
When does complexity help?
Complex models earn their keep when the data has non-linear relationships, high-dimensional interactions, or thousands of features, such as genomics, image classification, or natural language processing. For structured clinical data with 4-10 variables and a few hundred to a few thousand patients, the performance difference between logistic regression and a random forest is usually small.
Several published comparisons in clinical prediction modelling have shown this. The complex model wins on AUC by 0.01-0.03, but the logistic regression is easier to validate, easier to explain, and easier to deploy. In a resource-limited setting, those practical advantages matter more than a marginal accuracy gain.
There is also a reproducibility argument. A logistic regression model is fully described by its coefficients and intercept. Anyone with a calculator can reproduce the prediction. A gradient-boosted model with 500 trees, max depth of 6, and a learning rate of 0.1 requires the exact software version, the exact hyperparameters, and sometimes the exact random seed to reproduce. When a clinical partner asks 'can we verify this model independently,' the logistic regression answer is straightforward. The gradient-boosted answer involves shipping code, dependencies, and environment specifications.
The exception is genuinely non-linear data. If the relationship between a predictor and the outcome changes direction at a threshold (for example, both very low and very high BMI increase risk), a linear model will miss that pattern. In those cases, restricted cubic splines within a logistic regression framework can capture non-linearity while preserving interpretability. We use this approach when the data warrants it, but we do not default to non-linear methods without evidence that the relationship is non-linear.
The deployment advantage
Logistic regression models are trivial to deploy. The prediction is a weighted sum passed through a sigmoid function. It can be implemented in a spreadsheet, a mobile app, a web form, or a printed nomogram. There are no model loading steps, no dependency chains, and no GPU requirements. A clinic in rural Nigeria with intermittent internet access can run the model on a phone with no network connection.
This deployment simplicity also reduces the surface area for errors. When a prediction requires loading a serialised model object, initialising a runtime environment, and running inference through a framework, there are many points where things can go wrong silently. A logistic regression prediction computed from stored coefficients is transparent at every step. If the output looks wrong, you can trace the calculation by hand in five minutes.
Regulatory and institutional review processes are also simpler for logistic regression. Many hospital IT departments and ethics review boards have standard procedures for evaluating regression-based clinical tools. Presenting a neural network-based prediction tool to the same review board introduces questions about explainability, versioning, and failure modes that do not arise with a well-documented regression model.
Transparency as a design choice
All three of our live demos use logistic regression. This is a deliberate choice, not a limitation. The coefficients come from published, peer-reviewed research. The standardisation parameters come from the training data. Every step from input to output is traceable.
When a partner asks how the model works, we show them the equation. When a reviewer asks whether the model is appropriate for their population, they can inspect the coefficients and the training data characteristics. That level of transparency is what institutional partners expect, and it is what responsible analytics requires.
We have had conversations with partners who assumed that our use of logistic regression meant the models were less sophisticated or less accurate than competitors using deep learning. The conversation changes when we show them the calibration plots, the validation results across different patient subgroups, and the exact computation pathway from input to output. Sophistication is not measured by the complexity of the algorithm. It is measured by the rigour of the entire analytical process, from cohort definition through validation to deployment.