# Basic Concepts Of Statistics

In order to define the basic concepts of statistics, we need to deal with descriptive statistics. This branch deals with the description of experimental data. **It covers in particular the collection, organization and analysis of data. **The data describes the set of characteristics of certain objects belonging to the population.

According to Ignacio Cascos, a professor at Charles III University in Madrid, these are the basic concepts of statistics that everyone should know:

## 1. Population

The population is a **well-defined set of similar objects with characteristics of interest to observers.**

This can be limited or infinite. Thus, **the size of the population is the number of items it contains. **It is usually expressed with the letter *N* .

If the population is very large, it can be very expensive to conduct research. In some cases, it is impossible to take every factor into account. Because of this, researchers usually select certain elements from a population or *sample* .

## 2. Items

**The target is a single element in the population. **These elements do not necessarily have to be people. In psychology, however, objects are usually people.

## 3. Sample size

**A sample is a set of objects in a population** that reflects its characteristics as well as possible. If the sample size corresponds to the characteristics of the population, the sample is representative. In addition, the size of the sample is the number of items it contains. We indicate the sample size with the letter *n* .

If the sample and population sizes are the same, it means sampling the entire population.

## 4. Variables

**A variable (X) is a symbol that represents any property, number, or quantity of a population** that researchers can measure or calculate. Data (r) is a value that can change within a variable (hence the name). Its value depends on what it measures.

## Variable types

### Qualitative variable

This type of variable **takes values that correspond to non-quantitative properties of objects. ** Therefore, it cannot be said that one is more valuable than the other.

An example of such a variable could be gender. These variables are called qualitative because the differences between them are properties or characteristics.

### Original variable

**The original variable can be divided into groups. **In addition, researchers can set or arrange them based on their value. If you had qualitative variables, you could classify them.

**Think, for example, of school grades**. 10 is better than 9. 9 is better than 4.

### Quantitative variables

Quantitative variables take on numeric values. That means they can be measured in numbers. There are two types:

**A separate variable.**The set is finite or computable. For example, the number of children in a family.**Continuous variable.**The set is infinite or unknown. For example, time.

## Positions

In descriptive statistics, you can determine the position of your data using position measurement.

### Average

Mean means or metrics are typical or representative data values. Therefore, their purpose is to aggregate all data with a single value.

The most common means are **mode (qualitative variables), median (categorical variables), and mean (quantitative variables).**

**Like**. Fashion is the item that occurs most often. If there are more than one of these values, the variable is multimodal. In addition, the mode of any variable can be calculated.**Median**. It is calculated according to categorical variables. That is, at least half of the data is less than or equal to the median. Also, at least half of the data is equal to or greater than the median. If there is more than one median, the midpoint between the largest and smallest medians must be taken. This is the value in the snippet that serves as the median.**Average**. It is the most common or famous of all. You may also feel it as an average. Quantitative variables are needed to calculate it.**The mean is the geometric center.**Something strange happens to the average because it may not represent the sample, but it may not even represent the true value of the sample. In other words, this value may not be present in the sample.

## Last thoughts

Although many more concepts are used in statistics, these are perhaps the most important basic concepts in statistics. They allow you to organize and calculate statistics and data. Therefore, these are good tools for researchers and the scientific community. **The statistics provide a complete map of the survey results.**