"Have we discovered a new particle in physics?
Is a manufacturing process out of control?
What percentage of men are taller than Lebron James? How about taller than Yao Ming?
All of these questions can be answered using the concept of standard deviation.
For any set of data, the mean and standard deviation can be calculated. For example, five people may have the following amounts of money in their wallets: 21, 50, 62, 85, and 90. The mean is $61.60 and the standard deviation is $28.01.
How much does the data vary from the average? Standard deviation is a measure of spread, that is, how spread out a set of data is.
A low standard deviation tells us that the data is closely clustered around the mean (or average), while a high standard deviation indicates that the data is dispersed over a wider range of values.
It is used when the distribution of data is approximately normal, resembling a bell curve.
Standard deviation is commonly used to understand whether a specific data point is “standard” and expected or unusual and unexpected. Standard deviation is represented by the lowercase greek letter sigma. A data point’s distance from the mean can be measured by the number of standard deviations that it is above or below the mean. A data point that is beyond a certain number of standard deviations from the mean represents an outcome that is significantly above or below the average. This can be used to determine whether a result is statistically significant or part of expected variation, such as whether a bottle with an extra ounce of soda is to be expected or warrants further investigation into the production line.
The 68-95-99.7 rule tells us that about 68% of the data fall within one standard deviation of the mean. About 95% of data fall within two standard deviations of the mean. And about 99.7% of data fall within 3 standard deviations of the mean.
The average height of an American adult male is 5’10, with a standard deviation of 3 inches. Using the 68-95-99.7 rule, this means that 68% of American men are 5’10 plus or minus 3 inches, 95% of American men are 5’10 plus or minus 6 inches, and 99.7% of American men are 5’10 plus or minus 9 inches. So, this means only about .3% of American men deviate more than 9 inches from the average, with .15% taller than 6’7 and .15% shorter than 5’1. This reasoning suggests that Lebron James is 1 in 2500 and Yao Ming is 1 in 450 million.
In particle physics, scientists have what are called 5-sigma results, results that are five standard deviations above or below the mean. A result that varies this much can signify a discovery as it has only a 1 in 3.5 million chance that it is due to random fluctuation.
In summary, standard deviation is a measure of spread. Along with the mean, the standard deviation allows us to determine whether a value is statistically significant or part of expected variation."
I understand why some think this video is stupid and why others think it's great. Does the video touch on all points and does it demand data without reference? Yes, I would say it's informative but poorly made.
Thank you very much for the explanation. One question on min 2:29, if 5'10 is our average and "base" and the standard deviation is 3 inches. You write that the spread is 5'1 - 5'4 - 5'7 -5'10 (average) - 6'1 - 6'4 - 6'7 inches. Shouldn't it be 4'20 - 4'50 - 4'80 - 5'10 (average) - 5'40 - 5'70 - 6'0 inches? Thanks in advance.
Thanks for the great PowToon! Really great production quality. I'm not an expert on SD, thus I consulted your video. I love seeing experts in their filed find ways to communicate difficult concepts in concise and meaningful ways! Well done! (And adding a transcript - A+)
to Wood'N" Stuff...I agree totally. I thought I was the only one confused....ugh....but the video definitely made it worse. I wanted him to explain also where he got the standard deviation of $28.01....oh well
OKAY, so because I am not a math person, tell me if this is a correct assumption about how I should feel when I hear something is X standard deviation. 1 SD: worth noting, but fairly normal. 2 SD: somewhat remarkable. 3 SD: DAMN son, look at that! Anything more: An actually really crazy number, very unique.
I have to agree with the comment below me. This is NOT how you teach something so that people can comprehend it. There's an assumption within the video that the viewer comprehends the jargon used in this video. Why is it that people who want to teach this, revert to jargon to explain it. more confusing then helpful for sure.
Huzzah! Thank you!
I'm working creating a tabletop RPG for some friends of mine and the core mechanic uses dice pools with all kinds of different dice. Being able to calculate a standard deviation will be super helpful in balancing all the math.
If you're complaining about the quality of this video in any fashion, then you desperately need a cold cocktail on a mild and sunny day on a tropical beach likely no more than 1.5x standard deviations from where you are right now as you read this silly comment. If you're not complaining about this video, I wish you the same. This video's producer made YouTube just a little bit better by adding it.
Huh what the fuck are you talking about for one you going so damn fast my brain can't even wrap my head around what you just said to even try to understand it before you jumped on something else and now I'm confused slow the fuck down people are stupid
After searching google for a half hour and dealing with people who couldn’t explain anything to someone who doesn’t know math, this video gave me the straightforward answer I needed.
Thank you for actually providing information rather than trying to seem smart by making the explanation more complex than necessary.
It is understood that a "bell curve" naturally happens in most data used in the world. Process variation is defined as "sigma". There are 6 process variations
(3 on the left from the mean and 3 on the right from the mean). The separation is due to how the "bell" curve or the sample behavior changes drastically at these points (inside these specific ranges). Sorry for not being eloquent.
standard deviation can be used as a measure of dispersion for any data-set... that may or may-not come from a random variable which follows a probability distribution such as a normal distribution.
however, the concept becomes 'useful' (in calculation of probabilities or frequencies) if the distribution of the variable is known. especially useful when the distribution is symmetric - as in the case of a Normal distribution.
Although foreigners may now invest in A-shares, there is a monthly 20 percent limit on repatriation of funds to foreign countries.
Performance of A-shares.
Since its inception in 1990, including a major reform in 2002, the index has seen great fluctuations. Overall, however, it has grown along with the Chinese economy. The years 2015 to 2016 were a particularly difficult period, with a 52-week performance of -21.55 percent as of July 20, 2016.
As China grows from an emerging market to an advanced economy, there is substantial demand for Chinese equity. Stock exchange regulators continue efforts to make A-shares more broadly available to foreign investors and have them recognized by the global investing community.
In June 2017, the MSCI Emerging Markets Index announced a long-awaited decision it would add stocks to its index. According to CNBC, MSCI will add 222 China A Large Cap stocks to its benchmark emerging markets index gradually beginning in 2018. The MSCI website reveals the stocks it will list include the Bank of China, China Merchants Bank, Guotai Junan, Ping An Insurance, according to a document on Tsingtao Brewery, SAIC Motor, Suning Commerce and Spring Airlines.
Current Dividend Preference.
Participating Preferred Stock.
Convertible Preferred Stock.
Cumulative preferred stock includes a provision that requires the company to pay preferred shareholders all dividends, including those that were omitted in the past, before the common shareholders are able to receive their dividend payments.
Non-cumulative preferred stock does not issue any omitted or unpaid dividends. If the company chooses not to pay dividends in any given year, the shareholders of the non-cumulative preferred stock have no right or power to claim such forgone dividends at any time in the future.
Participating preferred stock provides its shareholders with the right to be paid dividends in an amount equal to the generally specified rate of preferred dividends, plus an additional dividend based on a predetermined condition. This additional dividend is typically designed to be paid out only if the amount of dividends received by common shareholders is greater than a predetermined per-share amount. If the company is liquidated, participating preferred shareholders may also have the right to be paid back the purchasing price of the stock as well as a pro-rata share of remaining proceeds received by common shareholders.
Significance to Investors.