K-means cluster analysis example

The example data includes 272 observations on two variables--eruption time in minutes and waiting time for the next eruption in minutes--for the Old Faithful geyser in Yellowstone National Park, Wyoming, USA. This data is available in many places, including the freeware R program.

Note

An original source is Hardle, W. (1991) Smoothing Techniques with Implementation in S. New York: Springer.

One reason that this data is featured in examples is that charts reveal that the observations on each input are clearly bimodal. For this reason, we use them to illustrate K-means clustering with two clusters specified.

Our analysis proceeds as usual: 

• Descriptive analysis
• Cluster analysis
• Cluster profiling

Descriptive analysis

Here is a histogram of eruption:

You can clearly see the bimodal nature of the distribution, with one center around 2 and another center around 4.5.

Here is a histogram of the waiting time to next eruption:

Again, you can clearly see the bimodal nature of the...