Data Science: Graphical Representation of Data

Graphical Representation of Data

 Basic graphical tools used in Statistics

There are several types of graphical data representation methods used in data science, including:

(i) Bar charts: 

These are used to compare the sizes of different categories or groups of data.

Here are the general steps for constructing a bar chart manually:

• Collect and organize the data: Gather the data that you want to display in the bar chart, and organize it in a way that makes sense for the bar chart. The data should be in the form of categories and their corresponding values.
• Determine the scales for the x- and y-axes: Decide on the ranges for the x- and y-axes, and the increments that will be used. This will help to ensure that the data is clearly and accurately represented in the chart.
• Draw the x- and y-axes: Use a ruler or straight edge to draw the x- and y-axes on a piece of graph paper. Be sure to label the axes and include a key or legend if necessary.
• Plot the data: Using the scales determined in step 2, plot the data on the graph by drawing a bar for each category. The height of each bar should correspond to the value for that category.
• Add labels and annotations: Label the x- and y-axes, and include a title for the chart that clearly describes what the chart is showing. Add any other necessary annotations or notes to the chart to provide context for the data.
• Check for accuracy: Review the chart to ensure that the data is accurately represented and that the chart is easy to understand. Make any necessary adjustments before finalizing the chart.
• Finalize the chart: Once the chart is complete, you can reproduce the chart on a larger scale or in a different format if needed.

It is also worth mentioning that, there are many software tools and libraries that can help you to construct bar charts in an easy and efficient way. It can save a lot of time and effort, and also allows you to customize and refine the chart in different ways.

(ii) Pie charts:

Here are the basic steps for manually constructing a pie chart:

• Collect and organize the data you want to display in the chart. The data should include the different categories and the values associated with each category that you want to compare.

• Determine the total value of all categories. This will be used to calculate the angle of each segment of the pie chart.

• Draw a large circle on a piece of paper or graphing software to represent the whole.

• Divide the circle into segments that represent the different categories. The size of each segment should be proportional to the value of that category. To calculate the size of each segment, divide the value of the category by the total value and multiply by 360 degrees.

• Label each segment with the category name and the value.

• Add a legend to the chart to explain the different categories represented by the different segments.

Finally, provide the chart with an appropriate title.

It's important to keep in mind that the above steps are for a basic pie chart, and there are many variations and customizations you can make based on your data, such as 3D pie charts, exploded pie charts, doughnut charts, etc.

Keep in mind that drawing the pie chart by hand can be challenging and time-consuming, especially if you have many categories and small differences in values. In that case, using a charting library or software would be a better option for creating a clear and accurate visualization.

NUMERICAL QUESTIONS 

here are some numerical examples of problems that can be represented using a bar chart:

 Example 1: The population of different countries: A bar chart or Pie Chart can be used to display the population of different countries. For example, the data might be organized as follows:

Which country has the highest population? Construct Bar and Pie Chart?

Bar Chart Representation

Pie Chart For Representing Graphical Display Of Data

Example 2: Number of visitors to a website by month

Construct Bar and Pie Chart?

(iii) Multiple Bar Chart: 

Here are the basic steps for manually constructing a multiple bar chart:

• Collect and organize the data you want to display in the chart. The data should include multiple variables that you want to compare.

• Determine the appropriate scales for the x and y axes. The x-axis should have a scale that corresponds to the categories you are comparing (e.g. different groups or time periods), and the y-axis should have a scale that corresponds to the values of the variables you are comparing.

• Draw the x and y axes on a piece of paper or graphing software. Label the axes with appropriate units and increments.

• Plot the data by drawing bars for each variable, with one bar for each category. The bars should be of equal width and should be separated by a small gap. The height of each bar should correspond to the value of the variable for that category.

• Add a legend to the chart to explain the different variables represented by the different colors or styles of bars.

• Finally, provide the chart with an appropriate title and labels for the x and y axis

Note: If you are drawing the chart by hand, you may need to use a ruler or other tools to ensure that the bars are the same width and are spaced evenly.

It's also important to keep in mind that the above steps are for a basic multiple bar chart, and there are many variations and customizations you can make based on your data, such as stacked bar charts, grouped bar charts, etc.

NUMERICAL QUESTIONS 

Question: Construct a Multiple Bar Diagram.

Example 1: Sales of different product categories by region:

Multiple Bar Diagram for the Example 1

Example 2: Monthly revenue of a company by division:

Example 3:A number of customer complaints by department and type:

Example 4: Number of accidents on a certain road by time of day and weather conditions:

Example 5: Number of employees by job title and gender:

Example 6: Number of visitors to a city by month and type of tourist:

(iv) Sub-Divided Bar Chart: 

• Determine the categories or variables that you want to compare in the sub-divided bar diagram.
• Choose a suitable scale for the y-axis and label it appropriately.
• Draw the main bars for each category, using the scale on the y-axis to determine the heights of the bars.
• Divide each main bar into sub-sections, representing the different sub-categories or sub-variables that you want to compare.
• Label the sub-sections within each main bar to indicate the specific sub-categories or sub-variables that they represent.
• Add a legend or key to indicate the meaning of the different colors or patterns used in the sub-sections.
• Add a title and x-axis label to the diagram to clearly communicate the information being presented.

NUMERICAL QUESTIONS 

Question: Construct a Sub Divided Bar Diagram.

Example1: Monthly revenue of a company by division and type of customer

Example 2: Monthly revenue of a company by division and type of customer

Example 3: A number of customer complaints by department and type of customer: