Standard deviation Definition and 271 Threads

Ok, so I'm sure that I worded the topic of this thread poorly, but I'm a little lost as to exactly how to explain my problem. As such, I'll just lay out everyting in some detail and hope those of you with more stats expertise will understand :o) The problem: * I have data from 5 subjects...

Ok I've got a maths exam on monday and one of the things that is going to be inside it is standard deviation. Problem is I don't get it one bit. I tried googling it but I didn't understand any of it. Could someone explain to me how I would find the estimated standard deviation for the...

I am working on a primatology project where I need to find a way to measure and plot the (somewhat arbitary) level of variation in behavior (ie from one individual to the next) within a single species and then compare it to another species level of variation. I have entered the data for the...

Can someone let me know how to compute the standard deviation on the TI-83.:smile: Thanks, Home Decoration

Just a quick question as I'm writing up my coursework. I'm calculating the standard deviation of a sample, my data is rate of reaction defined as \frac{1}{time} \times 10^{-3}. So my input data is say 0.847, but the absolute value is 0.000847. The standard deviation formula returned a value...

I have no idea how to start this problem or what equations I would need, if any. Below is the problem, and after that, I include my failed attempts at this problem. The problem: ------------------------------------------------------------------------ Students at Eastern Illinois University...

Let us assume that X has Bernoulli distribution, with P(X = 1) = p and P(X = 0) = q = 1 - p. Of course, E(X) = p and Var(X) = pq. Now, since pq < 1, standard deviation is bigger than variance. I have got the following question: Does this fact make standard deviations and theorems based on...

Umm its tough to see so I'll write the question too... The standard deviation of the annual growth rates of a mutual fund is an indicator of how volitile or risky the fund is. Determine the upper and lower limits of the annual growth rate for each fund, such that there is a 0.75 probability...

Hi everyone, I was wondering what the mathematical relationship between temperature and standard deviation in energy is. As I understand it, temperature is energy in random motion, and some sets of random data have a standard deviation from the "average". So how would the temperature of, say...

\textit{To get an estimate of your uncertainty, compute the standard deviation. My 4 distances are 150, 120, 100 and 100 parsecs (pc)} The average of my 4 distances is \[ \bar {x}=\frac{\sum\limits_{i=1}^n {x_i } }{n} \] \[ \bar {x}=\frac{150pc+120pc+100pc+100pc}{4}=117.5pc \]...

If you tossed two coins simultaneously 400 times, would you expect the standard deviation to be greater or less than it was 40 times? I think tossing 2 coins 400 times would give a greater standard deviation because the sample size is larger so the standard deviations can be quite far from...

Standard deviation? COIN TOSS HELP! I tossed a coin 20, 30 and 50 times are recorded number of heads and tails and to get the deviation I first subtracted the expected from the observed for both heads and tails then I squared this value and divided it by the number of events and then toook the...

*I have already posted this in another forum, but re-read the rules regarding homework questions.. Mods, I hope this is ok* Hey guys, I've got this question from my Statistics Homework and wondered if someone could point me to a website or supply some advice as to how to begin to solve the...

Here's the question: so, I said the mean (X) of delta is 0.0015 and the standard deviation (S) of delta is 0.000092 X_d=0.0015, S_d=0.000092 X_l=2.000, S_l=0.0081 I said Z=d/l\ thus\ X_z=X_d/X_l and the S_z^2=(C_d^2+C_l^2)/X_z^2 So, I did the following...

Well in physics lab we just did a lab where we calculated the acceleration do to gravity,this didn't include the air resistance, so the ligther stuff shouldn't be perfect. We took video of stuff falling and then put the data from that into mathematica and fitted a quadratic equation to it and...

Changes to Standard Deviation?? How many of you know that Standard Deviation has changed. It used to be:\sqrt{\frac{\Sigma(x_i - \overline{x})^2}{n}} And now it is:\sqrt{\frac{\Sigma(x_i - \overline{x})^2}{n - 1}} It is the Variance of data but square rooted: s^2 = \frac{\Sigma(x_i...

Why is the standard deviation \sigma =\sqrt{\frac{\sum_{i=1}^{n}\left( \overline{x}-x_{i}\right) ^{2}}{n-1}} and not \sigma =\frac{\sum_{i=1}^{n}\left| \overline{x}-x_{i}\right| }{n} or at least \sigma =\sqrt{\frac{\sum_{i=1}^{n}\left( \overline{x}-x_{i}\right) ^{2}}{n}}? I suppose that it...

I was given an assignment dealing with finding standard deviation. From the example given, I was able to do the assignment and get the correct answers, but I still don't understand standard deviation or its importance. Could someone explain standard deviation to me, or at least point me to...

I am having trouble with this question. Let X equal the number of flips of a fair coin that are required to observe the same face on consecutive flips. (a) Find the p.m.f. of X. if found the p.m.f. to be f(x) = (\frac{1}{2})^{x-1} for x=2,3,4,... (b) Give the values of the mean, variance...

Help please?? To anybody that can offer a hand. <x>=5, Standard Deviation = 2, median Mx=4.5, Quartile1=4, Quartile 2=6, xmin=0, xmax=9. After a linear tranform: y= -2x+1. What are <y>, Standard deviation y, median y, Q1y, Q2y, Ymin, Ymax. I was given this equation for...

We know that the standard deviation [sig] for a random walk, represented by a net distance d, to be approximately the square root of the total number of steps N, each of length L, from the origin. I. e., d~N1/2L~[sig]L. Does the angle attained after these steps also have a significant...