Representation and summary of data - measures of dispersion

• Method for discrete data

Q1 = n/4 - whole number - find mid-point of corresponding term and term above

              - decimal - round up and pick corresponding term

Q3 = 3n/4 - whole number - find mid-point of corresponding term and term above

               - decimal - round up and pick corresponding term

• Method for continuous data

Q1 = n/4 then use interpolation to find the corresponding value

Q3 = 3n/4 then use interpolation to find the corresponding value

• Interquarile range (IQR)

IQR = Q3-Q1

• xth percentile, Px

Find the…