Example – G rouped data Waiting times1 - 45 - 910 - 1415 - 1920 - 2930 - 3940 - 4950 + frequency91520152011100 Question: Waiting times, to the nearest minute, at a doctors surgery for 100 patients were recorded: Answer: Estimate the median and interquartile range of waiting times The median is the middle value: n/2 = 100/2 = 50 th value median = 14.5 + 9 2 6 median 44 15 – 19 class 14.519.5 Linear interpolation: Assume 15 values are evenly distributed in class 2 3 lies in class 15 - 19