## Variability

• Variability describes how far apart data points lie from each other & from center of the distribution
• Variability is also referred as spread, scatter or dispersion & is most commonly measured with the following
• Variance: Variance measures the dispersion of set of data points around the mean
• Standard deviation: average distance from mean
• We would have different formulas for
• Population Data
• Sample Data
• Variance:
• Population Variance:
• Formula:
• Sample Variance:
• Formula:
• Lets calculate variance for a sample data Refer Here
• Standard Deviation
• Sample Standard Deviation formula
• Population Standard Deviation formula
• You have the annual personal income from 11 people from Hyderabad. Decide whether you need to use sample or population formula for variance.
• Calculate the variance and standard deviation
• Refer Here for the excel
• Coeffecient of variation:
• This is referred as relative standard deviation
• Formula: `standard deviation/mean`
• Refer Here this excel sheet and calculate standard deviation for new york and hyderabad pizza prices
• Exercise: Calculate standard deviation and coefficient of variation for the following excel Refer Here

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