### 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.

### The power of a test

The power of a test is the probability of detecting a statistically significant effect when one actually occurs in the population under study.

### SKEWNESS AND KURTOSIS

Kurtosis and skewness are measures of asymmetry that describe such properties as the shape and asymmetry of the distribution under analysis. They provide us with information on...

### Quantiles, quartiles, percentiles (measures of location)

We use quantiles to determine the position of a given value against others in a group or population. Let's say you have received the results of your matriculation exams in...

### STUDENT T-TESTS

The Student's t-test group is used to compare two groups of results, measured by the arithmetic mean, against each other.

### PEARSON'S CHI-SQUARE TEST OF INDEPENDENCE

The chi-square test of independence is one of the most popular statistical tests. It is used to check whether there is a statistically significant relationship between two...

### Deciding to remove an item from the scale

Sometimes instead of asking a single question in a survey, we ask a whole set of questions, which are intended to be used later to build a scale.

### How to boost a decision tree algorithm

The decision tree is a popular and effective algorithm used primarily in classification work, but it also serves well in predicting quantitative phenomena.