Bias and Variance in ML: A Simple Guide for Understanding Your Machine Learning Model's Performance
Have you ever played a game with your friends and noticed that your performance can vary depending on the level or challenge? Machine learning models can also have a similar issue with performance variability, known as bias and variance. Bias: Bias is the overall difference between what the model predicts and what the correct answer should be, averaged across all examples. A model with high bias consistently makes the same types of errors, regardless of the specific input features or examples. To illustrate this concept, let's consider a regression model that predicts the price of a house based on its square footage, number of bedrooms, and location. When evaluating this model on a test dataset, we calculate the mean squared error (MSE) between the predicted prices and the actual prices across all examples in the test dataset. If the MSE is high, this suggests that the model is biased and consistently predicts prices that are too high or too low compared to the true values. To ca...