A few days ago I posted the raw data from a two month period over the summer (June 7- August 7) where we recorded putting green measurements. I took that data and graphed it in order to see if there is a correlation between these different measurements. On all the graphs, the red line indicates the desired threshold for what the USGA considers "tournament conditions." However, in the case of green speed, 11 feet is the goal for daily play according to my 'Golf Course Standards" document that's be approved and accepted by the Green Committee. These measurements were taken using the USGA's GS3 ball, shown below.
If you'd like to see how it works, here is a 3 minute instructional video. CLICK HERE to watch.
Green Speed is determined using a stimpmeter. The number is how many feet it rolled off the stimpmeter. As I've said before, it's a factor of friction- how much or how little is working on the golf ball as it rolls across the putting green.
Smoothness and Trueness are somewhat similar. The GS3 ball determines how much up and down movement there is on the ball in the case of smoothness and trueness is the measurement of side to side movement of the ball. You can see above that these graphs are quite similar. In both cases, the goal is to be below the red line on the graph.
Finally, firmness is determined using the GS3 ball after it is dropped on the green from a consistent height. The USGA created a tool that holds the GS3 ball which measures the indentation (ball mark) made on the putting green when the ball is dropped. The deeper the indentation, the softer the green. The goal is to be below the red line on the graph.
By knowing this data, I can look back and compare what maintenance practices were done on a particular day that influenced the particular measurement. The same goes for weather data. For example, a heavy rain event may be the cause for a drop in green speed. Or, a sand topdressing application may be the reason for a change in smoothness.