Shot to shot fps formula

[derekj]

Hi chaps, what is the formula I need to use to calculate the shot to shot variation please? I have 12 chronograph figures to use. Thank you. Derek

[Airsporter1st]

Hi chaps, what is the formula I need to use to calculate the shot to shot variation please? I have 12 chronograph figures to use. Thank you. Derek

Try this.

[robinghewitt]

Try this.

Blimey, beats my notion of fastest minus slowest

[gordon]

Now that`s handy, thanks for posting

[DT]

I think us airguners over complicate things. If you have a range of readings. The highest and lowest readings are obvious. The variation is the difference between highest and lowest. The average is all the readings added together, then divided by the number of readings..

Pernod..

[Airsporter1st]

Blimey, beats my notion of fastest minus slowest

I think us airguners over complicate things. If you have a range of readings. The highest and lowest readings are obvious. The variation is the difference between highest and lowest. The average is all the readings added together, then divided by the number of readings..

Pernod..

Depends what you want from the data I suppose.

I think the idea of using a proper statistical analysis is that it compensates for the odd flyer etc. and arguably therefore gives a more realistic representation of what the gun is doing, for comparative purposes.

Of course, you could simply discard the obvious fliers and make the calculation as DT suggests, but if fliers are a fairly regular occurrence, discarding them is akin to ignoring them on the target.

[gordon]

Just had a play.. these are from my HFT 500 after polishing the hammer and spring guide etc. and resetting the firing pot, because it fell out,!!!

180bar fill down to 82 bar.

100 shots.

low..760.

high..792.

Range..32.

Standard Deviation..5.80.

Mean Deviation 4.4086.

Variance.. 33.672

AA 4.52 8.4 gr out of the tin, indoors.

Regards Gordon

[angrybear]

Hi chaps, what is the formula I need to use to calculate the shot to shot variation please? I have 12 chronograph figures to use. Thank you. Derek

If you get a Pro-chrono digital, it works it all out for you.

[gordon]

And this is from shot 31 to 82 .
180 bar fill down to 110 bar

Population size:52

Mean (μ): 784.75
Median: 785
Modes: 783 787
Lowest value: 776
Highest value: 792
Range: 16
Interquartile range: 4
First quartile: 783
Third quartile: 787
Variance (σ2): 10.302884615385
Standard deviation (σ): 3.2098106821719
Quartile deviation: 2
Mean absolute deviation (MAD): 2.5865384615385


If I fill to approx. 166 in reality I put 180 bar this puts the rifle on its sweet spot approx. 52 shots, I`ve left it at that as it shoots really well and it only drops fractions after shot 82 .. Regards Gordon. ps I don`t know what I`m on about but I like to fiddle

[gordon]

If you get a Pro-chrono digital, it works it all out for you.

Now you tell me

[derekj]

Try this.

Excellent! Thanks for that mate, nice one I entered all 12 velocity readings and it says the standard deviation is 3.55. Is that the shot to shot consistency reading? Thanks. Derek

[angrybear]

Excellent! Thanks for that mate, nice one I entered all 12 velocity readings and it says the standard deviation is 3.55. Is that the shot to shot consistency reading? Thanks. Derek

Yes, it's a gauge of the consistency.

68% of the data falls in the +/- 1xSD of the average,
95.4% of the data is within +/- 2xSD,
99.7% is within +/- 3xSD

so using simple figures if your average was 1000 with an SD of 10,
68% of the shots will be 990-1010,
95.4% within 980-1020
99.7% within 970-1030.