# Charts

In charts, data is represented graphically, therefore they are used in statistics mainly to get an overview of the collected data and to prepare information in an easily understandable way.

The most frequently used charts in statistics are:

- Bar chart
- Histogram
- Scatterplot
- box plot

## Histogram

A histogram is a graphical representation of the frequency distribution of a metric variable. To display a distribution of data in a histogram, the data must first be divided into classes, also called bins. These classes or bins are then represented by rectangles that lie directly next to each other.

This is also the main difference to bar charts, in a bar chart the data are already grouped from the beginning and do not have to be divided into groups as in a histogram. This becomes graphically clear, as in a bar chart there is a distance between the bars.

### Bar chart vs. Histogram

A bar chart and a histogram are both types of graphical representations of data, but they are used to display different types of information.

A bar chart is used to represent discrete data, where the data is divided into separate categories. The height of each bar represents the frequency or quantity of the data that falls into that category.

A histogram, on the other hand, is used to represent continuous data, where the data is divided into a set of bins or intervals. The height of each bar represents the frequency or quantity of the data that falls into that bin or interval. The bars in a histogram are usually adjacent and there is no space between them.

In summary, the main difference between a bar chart and a histogram is the type of data they represent and the way the data is divided and displayed.

Accordingly, histograms are used for metric variables such as salary or age, and bar charts for ordinal or nominal variables such as gender or school grade.

## Example Histogram

The creation of graphical representations such as the histogram will now be explained using an example. The aim of the example is to graphically represent the frequency distribution of the results of a statistical test. The starting point is the table below with the respective scores of the 12 students.

This is how it works with DATAtab: Simply copy the above table into the Statistics Calculator, click on Descriptive Statistics and finally select the variable "Score".

You will then see the following graph in DATAtab, which allows you to visualize the results of the statistics exams of 12 students.

Student | Score |
---|---|

1 | 28 |

2 | 29 |

3 | 35 |

4 | 37 |

5 | 32 |

6 | 26 |

7 | 37 |

8 | 39 |

9 | 22 |

10 | 29 |

11 | 33 |

12 | 34 |

## Scatter Plots

Scatter plots are used in statistics to visualize correlations in data. In a scatterplot always two variables can be plotted, this is done by representing each pair of values of a case as a point in a coordinate system. If, for example, 10 persons are asked for their weight and height, the scatterplot shows 10 points.

With the help of the scatterplot you get a first indication of the correlation between the two visualized variables. If high values of one variable are associated with high values of the other variable, there is a positive correlation. If high values of one variable are associated with low values of the other variable, there is a negative correlation. If the points are randomly distributed, there is no correlation.

Furthermore, there can also be a non-linear relation, in this case there is a pattern in the distribution of the points, but no straight line can be drawn through the points.

## Create charts online

**Charts** are a valuable tool for visually presenting information. On
Datatab you can create your own **charts online and free of charge**.

With DATAtab-charts you can easily
**create your charts online**. To create a chart, simply select the chart
type you want to create and copy your data to the table above. Which chart you
create depends on what information you want to convey and the scale level of
your data. DATAtab charts are constantly being expanded, currently the
following charts are available:

## Create charts

Charts allow you to present complex information clearly and offer the reader the advantage that he can quickly get an overview of your results. In statistics, it is advisable to first examine the data with the help of the charts created, this already gives an indication of whether there are differences in the individual groups, for example. Afterwards, the visual results can be used to test hypotheses.

## Make bar chart

Bar charts are mostly used to graphically represent frequency tables, then the height of the bars corresponds to the frequency of each category. If the variables are metric, the height of the bar indicates the average value of the individual groups.

## Make boxplots

With a box plot you can visualize the mean value, the median and the dispersion of your data. It is often used to find differences in groups.

## Make Histograms

With a histogram you can display the frequency distribution of metric variables.

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