Bar charts are one of the most common charts in scientific work and they are mostly used to show either frequencies or averages. Depending on how the bars are arranged, a distinction is made between horizontal and vertical bar charts.
Bar chart for frequencies
A bar chart shows absolute and relative frequencies on a two-axis coordinate system.
- Horizontal bar chart: Frequencies are represented by horizontal bars and the y-axis plots the characteristic values.
- Vertical bar chart: Frequencies are represented by vertical bars and the x-axis plots the characteristic values.
Due to the simplicity of bar charts, they are often created in descriptive statistics. They provide a very quick overview of the ranking and frequencies of characteristic values.
Grouped bar charts
If two categorical variables are present, grouped bar charts can be created. In a grouped bar chart, the bars are grouped together. The groups result from the categories of one of the two variables, the categories of the other variable are represented by different colors.
In the example above, the groups were formed with the help of the variable fall consequence and the categories of the variable location are highlighted with different colors. This can of course also be reversed.
In grouped bar charts, either the frequency, the percent, or the percent in each group can be specified.
Bar chart for mean values
Of course, bar charts can be used to display not only frequencies, but also other characteristic values. In addition to frequencies, mean values are very often displayed. For this, a categorical and a metric variable must be present.
Error bars are a graphical representation of the scatter of data. With error bars you can see how accurate your measurement is and get an overview of the range of your data!
Error bars are drawn in graphs as vertical lines above and below the measured value. The error bar is usually calculated using the standard error, standard deviation or 95% confidence interval.
Example bar chart
The procedure for creating a bar chart with DATAtab is now explained in more detail using an example. The example assumes that in a course on statistics, the participants were asked which make of car they drive. The results can be presented clearly and easily in a bar chart:
This is how it works in DATAtab: In the Statistic Calculator you can easily create a bar chart for your data. To do this, copy your data into the table of the Statistics Calculator, click on Descriptive Statistics and select your variables.
If there is an additional categorical variable, DATAtab can display this information with additional bars with a different coloring. If, for example, the gender is also known as another variable, the results can be displayed as follows. The blue bars refer here to the "male", the orange bars describe the information of the "female".
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