measures of spread & dispersion

Question 1

range

Answer 1

• ignores bulk
• only concerned with extreme values
  biggest - smallest

Question 2

IQR

Answer 2

• measures the range of the middle 50% of the data
• Q1 = 25th percentile (0.25 * no. of observations)
• Q2 = 50th percentile (median)
• Q3 = 75th percentile (0.75 * no. of observations)
  IQR = Q3-Q1

Question 3

IQR (grouped data)

Answer 3

• no. * frequency

- Q1 = (no. * frequency) *0.25

Question 4

standard deviation

Answer 4

= square root of variance