Other models

In this section, we will see other models provided by Rattle in the Model tab, which aren't supervised learning. These methods are Linear and Logistic Regression, Neural Networks, and Survival Analysis.

Linear and Logistic Regression

Linear Regression is a statistical method to describe the relationship between one or more input variables and one or more output variables. The objective is to create a formula that models the relationships between input and output variables; in this way, we can use this formula to predict new observations.

Imagine you are the manager of a marina, your marina has a gas station and you need to predict the amount of gas oil you will sell during a summer day. On the Mediterranean coast, during the summer, the amount of gas oil sold is correlated to the temperature. The reason is obvious, on sunny days, the temperature rises and more tourists want to use their boats. The example is illustrated in this diagram:

Linear and Logistic Regression

Based on past experience, we know that on a day with a temperature of 26ºC, the gas station sold 3,000 liters, and on a 28ºC day, it sold 4,500 liters. In this example, we can assume that the relationship between Gas oil Sold and Temperature is described by this equation:

Linear and Logistic Regression

This equation describes the relationship between Gas oil Sold and Temperature. Using this equation and a weather forecast, we can predict the gas oil our gas station will sell tomorrow.

When our dataset has one output variable, we will call it Simple Linear Regression. If we have more than one output variable, we call it Multiple Linear Regression.

We use Linear Regression when the target variable is numerical. In classification tasks, when the target variable is categorical, we will use Logistic Regression. When the target variable has two possible values or classes, we can use binary or binomial Logistic Regression.

Neural Networks

The Neural Network model is a method that can be used as supervised or unsupervised learning. Neural Networks are especially useful for pattern recognition and time series prediction; real-world applications include facial recognition, character recognition, or stock prices.

Neural Networks are inspired by the human brain and have three main layers:

  • Input Layer: This layer receives the input data and passes them to the hidden layer.
  • Hidden Layer: This layer contains a number of interconnected nodes. These nodes, called neurons, are mathematical functions that create the predictions.
  • Output Layer: This layer creates the final prediction from the predictions done in the hidden layer.

Neural Networks work especially well, when the number of input or attributes in the observations is high. An important disadvantage of Neural Networks is that the Hidden Layer is a black box and the algorithm doesn't explain the value of the prediction.

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