Mean Squared Error

medium_mse.js

function mse(model, data) {
    let result = 0.0;
    for (let i = 0; i < data.length; ++i) {
      	const elem = data[i];
      	const x = elem.x;
        const y = elem.y;
        const y_hat = predict(x, model);
        const diff = y_hat - y;
        result += diff * diff;
    }
    return result / data.length;
}