Re: Formula for calculating SD?
Here is how to figure ES and SD.
EXAMPLE:
Shot 1) <span style="color: #FF0000">3,642fps</span> Shot 2) <span style="color: #FF0000">3,667fps</span> Shot 3) <span style="color: #FF0000">3,674fps</span>
Average Velocity=<span style="color: #3366FF">3,661fps</span>
Now you can calculate the following: (use the average fps to find the difference)
(<span style="color: #3366FF">3,661</span>-<span style="color: #FF0000">3,642</span>) Squared=<span style="font-weight: bold">361</span>
(<span style="color: #FF0000">3,667</span>-<span style="color: #3366FF">3,661</span>) Squared=<span style="font-weight: bold">36</span>
(<span style="color: #FF0000">3,674</span>-<span style="color: #3366FF">3,661</span>) Squared=<span style="font-weight: bold">169</span>
Now you would add the results:
<span style="font-weight: bold">361</span>
<span style="font-weight: bold">36</span>
<span style="text-decoration: underline"><span style="font-weight: bold">169</span>+</span>
<span style="font-weight: bold">566</span> divided by 3 (number of shots) Equals <span style="color: #33CC00">188.6</span>
<span style="color: #33CC00">188.6</span> the square root of this will give you the SD of <span style="color: #006600">13.73fps</span>
And the ES is the difference from the lowest velocity measured to the highest. In this case the ES is <span style="color: #660000">34fps</span>
<span style="font-weight: bold">ES of 34fps
SD of 13.73fps</span>