Machine learning is a computational method that analyzes data to identify patterns and make predictions or decisions.Machine learning is a branch of artificial intelligence where algorithms build models from data, revealing hidden patterns without explicit rule programming. Techniques include supervised learning (from labeled examples), unsupervised learning (clustering), and reinforcement learning (trial and error).
The term 'machine learning' was coined by Arthur Samuel in 1959 when he created a checkers-playing program. In 1957, Frank Rosenblatt built the perceptron, the first artificial neuron model. After a period of 'AI winter,' development resumed in the 1980s with the discovery of the backpropagation algorithm. In the 2010s, explosive growth came thanks to big data, GPUs, and deep architectures.
A parameterized model (e.g., a neural network or linear regression) is chosen. During training, the loss between predictions and true values is minimized using numerical optimization. The most common is stochastic gradient descent: at each step, parameters are updated in the direction of the negative gradient of the loss function on a random subset of data. For multi-layer networks, gradients are computed using the backpropagation algorithm, based on the chain rule of differentiation. Key issues: overfitting, vanishing gradient, hyperparameter selection.
Used for movie recommendations, speech recognition, and even diagnosing diseases from images.
The first neural network algorithm, the perceptron, was created back in 1958, but it didn’t live up to expectations at the time, and only decades later did neural networks experience a revival.
| MSE | variable | Mean squared error — mean squared error |
| n | variable | Number of observations — sample size |
| y_i | variable | Actual value for observation i — actual value |
| \hat{y}_i | variable | Predicted value for observation i — predicted value |
| \sum_{i=1}^{n} | operator | Sum over all observations from 1 to n — summation |
| MAE | variable | Mean absolute error — mean absolute error same as dependent variable |
| n | variable | Number of observations — sample size |
| y_i | variable | True value for observation i — true value same as dependent variable |
| \hat{y}_i | variable | Predicted value for observation i — predicted value same as dependent variable |
| \sum_{i=1}^n | operator | Sum over all observations from 1 to n — summation |
| |\cdot| | operator | Takes the absolute value of the difference — absolute value |























