# statistics

### The Three-Sigma Rule

The three-sigma rule is an important tool in statistics and quality management. In the context of data analysis, it allows the identification of outlier points that are...

### Segmentation: from grouping to classification

Segmentation is a key process in data analysis, dividing a data set into relatively homogeneous groups based on specific criteria. The purpose of segmentation is to identify...

### Outlier or anomaly? Detection of abnormal observations

Can one abnormal occurrence cause concern? Based on one deviation from the norm, should a red light start flashing? Of course! In many industries and businesses, an anomaly is a...

### Statistical inference

Statistical inference is the branch of statistics through which it becomes possible to describe, analyse and make inferences about the whole population on the basis of a sample.

### Outlier cases. Identification and significance in data analysis

In data analysis, it is important to identify unusual observations that are significantly different from the others. Such values, called outliers or outlier cases, can affect the...

### Levels of measurement

The level of measurement is one of the most important properties of variables. It determines which statistical tests will be available to the researcher during the course of the...

### Pearson's chi-square correlation test

Popular statistical tests include Pearson's chi-square tests. It is worth noting at the outset that this test has more than one application. In this material, I will discuss the...

### Entropy

Entropy is a measure of disorder or uncertainty in a probability distribution.

### Gini index

The Gini index is a measure of the concentration of a variable's distribution.

### Logistic regression

Regression is used to predict the value of the dependent (predicted) variable on the basis of the value of the independent variable or variables (predictors).

### From variance to the method of least squares

The mean is one of the most popular and widely used statistical measures. However, by itself, it is not an exhaustive indicator and only allows us to determine the central...

### Factor analysis

The aim of factor analysis is to explain as much of the variation as possible with as few variables as possible.

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