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standard
In statistics, the standard deviation (SD, also represented by the lower case Greek letter sigma σ for the population standard deviation or the Latin letter s for the sample standard deviation) is a measure that is used to quantify the amount of variation or dispersion of a set of data values. A low standard deviation indicates that the data points tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the data points are spread out over a wider range of values.
The standard deviation of a random variable, statistical population, data set, or probability distribution is the square root of its variance. It is algebraically simpler, though in practice less robust, than the average absolute deviation.
A useful property of the standard deviation is that, unlike the variance, it is expressed in the same units as the data.
In addition to expressing the variability of a population, the standard deviation is commonly used to measure confidence in statistical conclusions. For example, the margin of error in polling data is determined by calculating the expected standard deviation in the results if the same poll were to be conducted multiple times. This derivation of a standard deviation is often called the "standard error" of the estimate or "standard error of the mean" when referring to a mean. It is computed as the standard deviation of all the means that would be computed from that population if an infinite number of samples were drawn and a mean for each sample were computed.
The standard deviation of a population and the standard error of a statistic derived from that population (such as the mean) are quite different but related (related by the inverse of the square root of the number of observations). The reported margin of error of a poll is computed from the standard error of the mean (or alternatively from the product of the standard deviation of the population and the inverse of the square root of the sample size, which is the same thing) and is typically about twice the standard deviation—the half-width of a 95 percent confidence interval.
In science, many researchers report the standard deviation of experimental data, and only effects that fall much farther than two standard deviations away from what would have been expected are considered statistically significant—normal random error or variation in the measurements is in this way distinguished from likely genuine effects or associations. The standard deviation is also important in finance, where the standard deviation on the rate of return on an investment is a measure of the volatility of the investment.
When only a sample of data from a population is available, the term standard deviation of the sample or sample standard deviation can refer to either the above-mentioned quantity as applied to those data, or to a modified quantity that is an unbiased estimate of the population standard deviation (the standard deviation of the entire population).
Gun stuff cleanout. Found this in a MAGPUL box, doesn't lool like it's ever been used but I wouldn't wager it. Looks good though, 25 pickup in Hillsboro, 30 if you want it shipped to you. Trade for 100 rds cheap 9mm ammo.
Here's a link...
Will come with original box,Two AUG Pmags, A single point sling, Magpul sling mount, Manticore arms brass deflector and a Streamlight pro tac rail mount 1000 lumen light.
I’m interested in:
Tavor 7
MK23
Desert Tech MDRX 5.56 or .308
Will consider other trade offers and half trade/half cash,I...
I'm helping with a budget build for a friend. He has a commercial buffer tube, and I don't have a spare buttstock for that size tube. Thought I'd ask here, if anyone has a commercial tube standard style 6 position black AR buttstock they want to part with cheaply? Alternatively, a mil-spec...
Will come with original box and two AUG pmags and a manticore arms brass deflector,Only want to trade and am In no rush, I am not interested in any AR’s.
Trade interest are
HK MK23
Tavor 7
Desert tech MDRX .308
Only a few hundred rounds fired out of it,Comes with 2 AUG Pmags and original box,It uses AUG mags,Looking to trade for a Tavor 7 or a desert tech rifle,I’ll listen to trade offers as well.
CROSS POSTED
PLEASE POST I'LL TAKE IT SO IT IS TIME STAMPED
On any trades if would you pm me that much be appreciated
PM what got and what think is fair
Please only post "I'll take in the listing
Meet at FFL in South End Auburn Puyallup Tacoma
American Western Arms 45 long Colt barrel length...
For sale, my super slick High Standard Supermatic Citation .22 target pistol! These are the gold standard by which all others are judged. This one is fully tuned and is more accurate then you! Comes with 2 HS factory mags, and 2 aftermarket mags that are adjusted and tuned, all 4 run flawlessly...
Comes with the following:
Original box & documents
x3 17 rd magaziness
all original components
Only put a box of 50 rds through the gun. Still in brand new condition. Looking to recede the collection.
*Buyer pays transfer fees*
*prices are firm*
*local FFL in person deals only*
thank you...
For sale High Standard Sentinel Imperial .22 LR 9 shot revolver in nice condition. Selling some of my Uncles firearms for his wife. Comes with box and paperwork. He had 2 and sold one decades ago and got the boxes mixed up so the serial on the gun and box don’t match. See pics $375.00 thanks...
For sale or trade P220 Legion with stock barrel and a threaded barrel (.578x28) from the sig store. I think less that 2 boxes of ammo fired , has be fired suppressed and functions perfectly.
Comes with legion case, factory plastic case and all stuff it came with new.
I’m switching back to...