The interquartile range is sometimes also called the interquantile range. It must be noted that R computes the IQR differently for some reason. You can look up the R documentation to see what they do but notice that you can force R to use the standard approach as well. Below, for example, the interactive cell determine the IQR using R’s preferred method. However, to use the method from this text, you can make the function call IQR(data, type=2). This might be helpful to know when working on some WeBWorK exercises where the author could be using R to compute the correct answer.