Measures of central tendency like the mean and measures of variation like standard deviation are sufficient for describing products and processes because they provide key metrics on average performance and how much data points deviate from the average. Standard deviation measures the average amount of deviation from the mean, while variance measures the average of the squared deviations from the mean and thus gives the spread or variability of a distribution.

1. a) Why are the measures of central tendency along with the
measures of variation considered to be sufficient, when
describing the characteristics of a product or a process? Provide
examples that support your answer
b) What is the difference between standard deviation and
variance? Explain your rationale