11,11.2,11.7,12.2,12.4,12.6,12.8,12.9,13.1,13.3,13.8,14.2,14.3,14.3,16.5,17.6,18

Determine whether the range or the IQR best describes the spread of the dataset

The range would be the best measure to describe the spread of the dataset, as it gives the overall difference between the highest and lowest values in the data set.