How to Visualize Numerical Variables

• To Visualize Numerical Variables we use the following
  • Frequency Distribution Tables
  • Histograms
• Consider the following dataset with each numerical variable appearing only once
• It makes more sense to group the numerical data into intervals
• Generally statisticians prefer 5 to 20 intervals, but it depends on volume of the data
• The formula for interval width

(largest number - smallest number)/number of desired intervals

• Then according to convience we can round the interval width
• A number is included in an interval if that number
  • Greater than lower bound
  • is lower and equal to upper bound
• The frequency distribution table will be as shown below
• Histograms:
  • These are one of the most common ways to reprsent numerical data.
  • Each bar has width of the interval.

Exercise: Represent the Frequency Distribution table and histogram for the following data

• Refer Here for the excel with dataset

• Frequency Distribution Table:

• Histogram

Two Variable Relationships

• Till now we have been dealing with single variables (Categorical and numerical variables)
• Now lets try to focus on how to visualize relationship between two variables
• For this lets start with categorical variables
  • Cross Tables (Contingency tables):
    • These are used to represent categorical variables.
    • One set of categories is labelling the rows and other set is labelling the columns
  • Side by Side Bar Chart: A common way to represent data from a cross table is by using a side by side bar chart
  • Refer Here for the excel sheet
• When we want to represent relationship between two numerical variables in the same graph, we usually use a scatter plot