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
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Refer Here for the excel with dataset
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Frequency Distribution Table:
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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
- Cross Tables (Contingency tables):
- When we want to represent relationship between two numerical variables in the same graph, we usually use a scatter plot