*This Blog entry is from the Summary Statistics and Basic Plots section in **Learn R**.*

Quartiles, which divides the vector up into four chunks which are equally sized, is one means to estimate spread. The IQR() function allocates the entries in a vector and provides explanation of the thresholds, returning the range between the end of the first quartile and the start of the third quartile. To establish quartiles type:

`IQR(AAPL$Interim_Close)`

Run the line of script to console:

To obtain more granularity around the range calculated using the IQR() function, use the quantile() function by typing:

`quantile(AAPL$Interim_Close)`

Run the line of script to console:

The first quartile is 107.510, the second quartile is 171.195 and the third quartile is 392.575, values which provide a measure of spread and coupled with other summary statistics can support a further visualization in the form of a box plot, as explained in later Blog entries.