How Data Visualization Works!
By: Mubarak Ganiyu
Tags: Data Science, Statistics, Charts, Data, Data Visualization

Horizontal bar charts are better at presenting data in either an ascending or descending order. Vertical bar charts are better at presenting data without using a sequential numeric order especially when only one data point matters.

Pie Chart

A pie chart is a chart that compares the magnitude of how different data point contributes to a whole. Each data point has a percentage that can be represented like a slice of pie which adds up to a full pie. That’s why it is called pie chart. The bigger the percentage, the bigger the slice and vice versa. All the percentages add up to 100%.

A pie chart of how the premier league teams have contributed in terms of goal scored by the premier league 2019/20 mid-season while highlighting the highest.

In the above pie chart, there is a circle with all the percentages adding up to 100%. To its right, there is a legend for all the labels of the slices.

Scatter Plot

A scatter plot is a plot that compares two numerical sets of values of two variables with one another. It places the numbers of one of the variables on the horizontal axis (x-axis) and the other on the vertical axis (y-axis). Then, it plots data points as symbols where the numerical values of the data point intersect on the graphs.

After plotting these symbols, further calculations can be carried out to measure the strength of the relationships of the two variables. This is done using the correlation coefficient. The correlation coefficient ranges from -1 to +1. A negative value signifies that they have an inverse relationship i.e as x increases, y decreases and vice versa. A positive value signifies that they have a direct relationship i.e as x increases, y increases. The closer the correlation coefficient is to |1|, the more perfect it is.

Another useful ability of the scatter plot is to create a regression line. By creating an equation that uses the independent variables on the x-axis to predict the dependent variables on the y-axis, a regression line is built.

A scatter plot showing how points accumulated vary with goal scored by premier league teams by mid-season 2019/20

Histogram

A histogram is a graphing mechanism used to count the number of times a numerical value appears in a given data set. It does this by grouping the numerical values into different groups within a fixed width of certain numbers. It counts the number of times the numerical values in each group appears and utilizes a bar to present its frequency. The more frequent the numerical values in a group is, the bigger the bar.

A histogram of FIFA 19 players’ ratings.

The graph above is a normally skewed data because most of the data sits right in the middle. This suggests that mean=median=mode. If most of the data are on the left side of the graph, it is called positively skewed, implying that mode<median<mean. If most of the data are on the right side of the graph, it is called negatively skewed, implying that mode>median>mean. The biggest bar is called the mode because it consists of the highest frequently occurring numerical values.

Line Chart

A line chart is a chart that is mostly used to show how a certain variable has changed over a period of time. It does this by plotting time on the x-axis and plotting the variable on the y-axis. It connects preceding data points with following data points using lines.