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As a Matter of Fact, You Should Start Reloading
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<blockquote data-quote="dsculley" data-source="post: 1350155" data-attributes="member: 77514"><p>Very nicely written article. I do have one issue though. </p><p></p><p>The author states he is a scientist in his day job. As such, he should understand statistics. When he is describing ES and SD, he gets a bit off base. A caveat before I proceed: We do not run enough rounds over a chronograph to get statistically significant data. To do so would burn up too much barrel life. We do get a good approximation of the true SD. The relationship between SD and true ES for this load is: ES = 6 * SD. The ES that we get from our chronograph data is OBSERVED ES. When he stated that his .308 load had SD of 8 & ES of 32 may be what he observed but is a bit misleading. His OBSERVED ES may be 32 but the true ES for the population is 48 if the SD is correct. The 6.5 data has the same type error. </p><p></p><p>When we shoot a sample, it would be surprising if we see the actual outer limits of our load. That why SD is so important. Once I settle on a load, I will usually chronograph this load for several range trips and combine the data. In this manner, I can get better statistical data. </p><p></p><p>Perhaps I am splitting hairs, but I see people on these forums that say they have an SD of X and an ES of YY, yet they have fliers they can't explain. Those fliers are due to the true ES for the load being much larger than they believe!</p><p></p><p>FWIW</p></blockquote><p></p>
[QUOTE="dsculley, post: 1350155, member: 77514"] Very nicely written article. I do have one issue though. The author states he is a scientist in his day job. As such, he should understand statistics. When he is describing ES and SD, he gets a bit off base. A caveat before I proceed: We do not run enough rounds over a chronograph to get statistically significant data. To do so would burn up too much barrel life. We do get a good approximation of the true SD. The relationship between SD and true ES for this load is: ES = 6 * SD. The ES that we get from our chronograph data is OBSERVED ES. When he stated that his .308 load had SD of 8 & ES of 32 may be what he observed but is a bit misleading. His OBSERVED ES may be 32 but the true ES for the population is 48 if the SD is correct. The 6.5 data has the same type error. When we shoot a sample, it would be surprising if we see the actual outer limits of our load. That why SD is so important. Once I settle on a load, I will usually chronograph this load for several range trips and combine the data. In this manner, I can get better statistical data. Perhaps I am splitting hairs, but I see people on these forums that say they have an SD of X and an ES of YY, yet they have fliers they can't explain. Those fliers are due to the true ES for the load being much larger than they believe! FWIW [/QUOTE]
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As a Matter of Fact, You Should Start Reloading
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