> Each SmartBroom has four sensors in the broom head that relay data to a small display unit. Hamilton took one for a spin down the ice, and the data was instantaneous — line graphs along with a slew of numbers that showed his force in pounds and his stroke rate in hertz. Hamilton also pointed to a figure that he described as his “sweeping performance index,” or S.P.I., a metric that combines power and speed in one easy-to-digest figure.

Is there an obvious true way to reach that SPI metric? Is it possible that optimizing for the broom-provided SPI gives you non-optimized performance? I would assume that you would need temperature measurements from the ground/ice since the article implies that's the function of sweeping:

> A quick primer on sweeping: It is important. The science behind it is much more complicated than people think. The simplified version is that sweeping slightly increases the temperature of the ice while creating micro-scratches on the surface. The result is that players are better able to control for distance and trajectory as the rock travels down the sheet. The sport hinges on precision, so every brush stroke counts.

Am I missing something?