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Questions tagged [standard-deviation]

In Probability and Statistics, the standard deviation of a statistical population or data set is a measure of how much variation or dispersion exists from its average value. It is defined as the square root of the variance. Use this tag alongside (statistics).

In Probability and Statistics, the standard deviation of a statistical population or data set is a measure of how much variation or dispersion exists from its average value. It is defined as the square root of the variance.

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Confusion with effect of averaging on standard deviation

First of all, I was reading a text and stuck with this part: Now regarding the above quote, I want to give two scenarios I made up to make my question clear: Scenario 1: Imagine we take N measurements from same sensor, and each measurement consists…
cm64
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Interquartile Rang concept / Problem?

If a set of data consists of only the first ten positive mulitple of $5$, what is the interquartile range of the set ? I have tried to solve but my answer is wrong..
SSK
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How do I determine a standard deviation with the mean and range known?

How do I determine a Standard deviation with the mean and range known?
Betty
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How to calculate the standard deviation of a variable

I have determined the slope of a linear fit and its standard deviation. Now I need to calculate k, which is 1/slope, but I don’t know to calculate the standard deviation of k. Is it 1/standard deviation of slope? If not, can someone, please, shine…
tmg28
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What's so special about the number '2' in the standard deviation?

If I'm not mistaking standard deviation is defined as $\sigma = \sqrt{\frac{1}{N} \sum_{i=1}^N (x_i - \mu)^2}$ .You could rewrite this as $\sigma = (\frac{1}{N} \sum_{i=1}^N |x_i - \mu|^c)^\frac{1}{c}$ where $c=2$. This makes me wonder: What is…
Garo
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Scaling average and standard deviation

I want to "scale" some numbers and associated standard deviation. I am analyzing the data of content in urine for x amount of intake of a certain chemical: time(d) value sd 1 0.5 0.25 7 0.2 0.12 If I want to scale…
DPdl
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Portfolio Standard Deviation equation

I'm trying to understand what this portfolio standard deviation equation means in the slide screenshot as marked. If someone could help me explain how this equation works, that would be great. When I read it, I read that standard deviation = (r-…
Daniel Kim
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Standard deviation above maximum possible value

I calculated a mean and the standard deviation for it. The mean it at 99%, the standard deviation is 5%. In case I plot that, the upper end of the standard deviation will be above 100% which is not possible in reality. The following image shows an…
54654654
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Different methods of computing standard deviation not agreeing

I have been assigned the following problem: Given numbers -25, 2, 3, 8, 10, 14, 18, 21, 32 You are told the mean of the numbers is 9.222 and the mean of their square is 309.666. What is the sample standard deviation? The answer is given…
Kirsten
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Standard Deviation: The average weight of a set X of 100 bags of rice is 90 pounds

a. A>B b. A 48 (the different between -3σ and 3σ which is 114-66=48) Please correct me if I'm…
Tui
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Finding a percentile in Excel

I am writing a program using excel and I need to find the percentage of a number. I have a few sample numbers and their percentages. 2.3% - 5.013368 5.0% - 5.238858 10.0% - 5.480078 25.0% - 5.908320 50.0% - 6.423700 75.0% - 6.984281 90.0% -…
Thomas Makai Post
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How do I find standard deviation in this problem?

In the ordered line : X: 4, 5, 9, 10, 11, 13, 16 P(X) 0.12, 0.1, 0.11,0.11,0.14,0.34,0,08 what is standard deviation? the mean is 10.31 Can you guys help me to find the standard deviation?
Hoàng Oanh Lê
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Algebra standard deviation

The average math score on the SAT for Melon Valley High School is 500. The standard deviation is 25 points. If 300 students take the test how many students will score between 475 and 525? Question 4 options: 284 340 204 50%
Creepy Freak
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Looking for an explanation over a standard deviation formula in C#

I found the following standard deviation formula by Victor Chen in a stackoverflow thread. I'm trying to understand why he calculates it like this: Math.Sqrt(sumOfDerivationAverage - (average*average));. The standard deviation is usually…
nop
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Finding Z-Value from Percentile

So I am just starting to work with standard distribution and deviation. I was wondering how to find the z-value of a percent. For example: Which z-value corresponds to the bottom 10% of standard distribution?
Ishani Tarkar
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