Without technology to draw the graphs this would be impossible to do efficiently. Clustering shows up most clearly on a dotplot. The Old Faithful dataset shows two clusters centred around 2 minutes and 4.5 minutes. A dotplot shows granularity as stacks of dots separated by gaps. By default, discrete data has some granularity as only certain values are possible.
Continuous data can show granularity if the data is rounded.
The Old Faithful dataset shows evidence of granularity. By examining the original data it becomes clear that this is the result of the data being rounded to one decimal place and is not a feature of the data itself. Other Features With the availability of computers and low cost statistics software it is possible to calculate summary statistics and generate graphical displays very rapidly. The choice of bin width of a histogram can markedly alter the apparent shape of the data, especially if the data is not uni-modal. As they are so quick to generate, it may be worth our while looking at some alternative histograms to see what they show.