Watch the animation for calculating the interquartile and quartile range and then consider the question below.

Why use these techniques? Is it appropriate?

  • Using quartiles show us how spread out the data is in a set of data.
  • The interquartile and quartile range tells us about the spread of the set of data. The quartile and interquartile range split the data into quarters, just as the median splits the set of data in half.

Evaluate the strengths and limitations of calculating the quartile range.

Strengths
Limitations

Strengths of calculating the quartile range:

  • Anomalies (high or low numbers) and skewed data are less likely to affect the result (unlike using the range or mean).

Weaknesses of using the quartile range:

  • Is a more difficult calculation than the range or mean
  • Does not include all the data in the data set as part of the calculation.