The purpose of this video is to describe differences between the Garmin Xero C1 Pro and LabRadar chronographs. While there was no difference in the overall average velocities derived from the Garmin and LabRadar, there was a difference in the standard deviation calculation between them. Also, a round up bias was detected in the LabRadar that was not present in the Garmin. The difference in the standard deviation calculation is rooted in the various ways to calculate standard deviation. The two major differences in calculating standard deviation are population and samplebased calculations. The Garmin utilizes a populationbased equation and the LabRadar uses a variant of a samplebased calculation. The example illustrated in the video shows the difference but is illustrated here too:
For the same three shots, the Garmin measured them at: 3227.4, 3228.4, and 3224.1 which is an average of 3226.6 which is what was read from the Garmin. The standard deviation was 1.8 and this calculation was confirmed as a populationbased standard deviation. The LabRadar measured the velocities as: 3228, 3226, and 3213 which is an average of 3222.3 but the Labradar read 3223 (a round up bias). The standard deviation was 7.9 and this calculation was confirmed to be a samplebased standard deviation. The standard deviation should be a populationbased standard deviation since there is no sampling from a population going on when shooting. When shooting, you shoot a definitive amount of shots that represent your entire population. In the example, the LabRadar should have used a populationbased equation and the standard deviation should have been 6.65. The Garmin uses the correct calculation for standard deviation. Implications for this major difference are discussed in the video.
Garmin:
https://www.garmin.com/enUS/p/771164
LabRadar:
https://mylabradar.com/