deviation Definition and 402 Threads

I am an independent researcher ready to compile data from an experiment. I have a set of measurements that include the uncertainties of measurement. If I calculate the mean for the set (and thus the standard deviation) do I need to include the uncertainties when doing this calculation?

I am an independent researcher doing a physics experiment. I have collected data and want to report the data with the uncertainities included, etc. I have taken a set of readings and I know how to calculate the mean and standard deviation. What I don't know is do I include the absolute...

Optics, prism and angle of deviation 1. Angle of incidence, emergence and deviation are respectively 30, 60 and 45 degree. 2. 3. I think that it is irrespective of the refractive index.

I'm new to studying statistics but it seems to me like standard deviation and kurtosis measure the same thing. The higher the standard deviation, the more spread out the data is, while the lower the kurtosis the more spread out the data is. I'm sure I'm wrong about this so can someone help...

I am a little confused about the justification behind what we do with things we believe to be poisson distributed. Take for instance, gamma-decay counts from a scintillation detector. Suppose we got 100 counts using a 1 minute integration time. We would then assume that the distribution of...

I went for a lecture and the lecturer said that the square of the difference between the x sub i and the mean is the take precaution of the negative value. This has been bugging me , i was wondering why don't they just take absolute because there is a difference between ...

What are the advantages of using the absolute mean deviation over the standard deviation. Is it possible to show a simple example where the former is more (or less) appropriate? Also, related to the mean deviation is my own variation. Does it have a name? Instead of calculating the absolute...

Hello again, I have a question here that asks me to find how large a sample size is, but I have no Standard deviation. How would you tackle this> How large a sample size do we need to estimate the mean annual income of natives in New York, correct to within $1000 with probability 0.99? No...

Homework Statement Given some data set, (x,y), fit to the the curve y=bx^2+a by minimizing the square of the deviation. Preferred to use matrices. Homework Equations The deviation for the ith data point is simply: d_i^2=(y_i-y)^2=(y-bx_i^2-a)^2 The Attempt at a Solution If I understand...

I am comparing two RMS error time-series and I would like to generate error bars on the RMS results. I think the RMS error is a standard deviation of an assumed zero mean process, and I have the gut feeling that this should be the standard deviation of the sample standard deviation. Is that...

1. An airline's flights have a mean arrival time of 5.8 min late with standard deviation of 2.1 min. What would be the appropriate x - scale for a histogram? 2. http://www.mathsrevision.net/gcse/sdeviation2.gif 3. I tried to do this problem, but I couldn't think of anyway to find...

Homework Statement A health physicist is testing a new detector and places it near a weak radioactive sample. In five separate 10-second intervals, the detector counts the following numbers of radioactive emissions: 16, 21, 13, 12, 15. a) Find the mean and standard deviation (SD) of...

Homework Statement 1) A random sample of 26 students who are enrolled in College A was taken and their SAT scores were recorded. The sample mean is 548 and the sample standard deviation is s=57. Assume population is normally distributed. a) Find a 98% confdience interval for the standard...

hello, how can i find out the angle of deviation for plano-concave lenses. thanks

For some given statistics (e.g. Fermi-Dirac or Bose-Einstein), once we know the average number of particles at state r, it is easy to calculate the dispersion by calculating \overline{(\Delta n_r)^2} = -\frac{1}{\beta}\frac{\partial \bar{n}_r}{\partial \epsilon_r} and the total number of...

Homework Statement I am doing a chemistry lab and I am going to be commenting on the precision of my data in my report I figure that calculating the mean deviation is the best way to do that. I had 6 separate trials in this experiment. I have already calculated the mean which is the same as...

Homework Statement Data set in X with mean xbar = 100 and standard deviation Sx = 10 Find ybar and Sy for 2(Yi-5)/10 + 7 Homework Equations The Attempt at a Solution All the problems I have seen are in the form yi = axi + b in which case the mean ybar = a(xbar) + b and...

Homework Statement The resistances of 50 resistors are measured and the results recorded are as follows: Resistance x Frequency 1.) 5 x 17, 2.) 5.5 x 12, 3.) 6 x 10, 4.) 6.5 x 6, 5.) 7 x 5) Calculate standard deviation of the measurements Homework Equations The...

There are two things I don't understand here: Firstly, why in the standard deviation expression we use the Q operator instead of the Q value itself? Writting Q seemed more natural and then in the next expression I would just stick the corresponding operator. Which would lead to the same result...

Much to the annoyance of my boyfriend, I have this deviation that I like to watch 'make-over' programs (Next top model, Project catwalk). I just watched another such episode (Looking Good), but seeing someone transform like this is just fun to watch (and it is not over the top like some of the...

hello can anyone explain what the difference is between RMSE and standard deviation. I am using RMSE in multivariate analysis but is it just the standard dev. why another name?

What is the formula for standard deviation?

Hey guys, Just a question which has been puzzling me for some time. I am told that means of samples of a population can be normally distributed with mean of \mu and with standard deviation of \sigma/\sqrt{}n Can someone please explain to me how the standard deviation is derived or is it...

Homework Statement The scores on an exam are normally distributed, with a mean of 77 and a standard deviation of 5. What percent of the scores are greater than 87? Homework Equations The Attempt at a Solution I don't understand what it is exactly that I have to do to get the...

Homework Statement I am comparing a normal DNA decamer molecule with one in which the two strands are only connected by the two base pairs on one of the ends. It was determined that the potential energies of both DNA molecules are negative, with values for the normal DNA much more negative...

Homework Statement Due to the expense involved, car crash tests often use small samples. When 5 BMW cars are crashed under standard conditions, the repair costs (in dollars) are as shown in accompanying list. Use 0.05 significance level to test the claim that the mean for all BMW cars is...

Hi I am reading a popular physics book. It discusses the test of Einsteins theory by Eddington at the eclipse. "The deviation of the light was double that predicted by Newton's physics" Why does classical physics predict any deviation of light by gravity, did light have a mass in...

Hi, You know famous equation, \frac{d<A>}{dt} = <\frac{i}{\hbar}[\hat{H},\hat{A}] + \frac{\partial\hat{H}}{\partial t} > But liboff said if \frac{\partial \hat{A} }{\partial t} = 0 then, \frac{d<\hat{A}>}{dt} = 0 this is the proof \frac{d<A>}{dt} =...

Homework Statement Recalling that k=R/Na (Na is Avogadro's number), show that the density of fluctuations of an ideal gas are given by : <(dp)^2> / p^2 = 1 / (N*Na) where p is the density (mass/V) That is, the relative mean square density deviation is the reciprocal of the number of...

1. Homework Statement The alpha particles used by Rutherford had a kinetic energy of 7.7 MeV and, for a head-on collision would get to within a distance of 3×10-14m of the centre of the gold nucleus. However the actual radius of a gold nucleus is approximately 7×10-15m. 2. Homework Equations...

If the gravitation has very very tiny deviation from inverse square law！our solar system became unstable? If so ,how long people on the Earth can notice it? Thank you in advance!

If the gravitation has very very tiny deviation from inverse square law！our solar system became unstable? If so ,how long people on the Earth can notice it?

Hello, The standard deviation is calculated as: http://www.mathsrevision.net/gcse/sdeviation2.gif Now the problem I have is that how you calculate the standard deviation (more accurately?) over both samplesvif you have two samples of different size, n1 and n2, in which the level of the...

Homework Statement If there are 4 children in a family, find the probability of getting exactly 3 girls. Find the mean, variance, and standard deviation. Use two different methods(binomial distribution method and general probability distribution method). Homework Equations Binomial...

"Normalizing" standard deviation between two data sets I have a baseline set of data collected which has a standard deviation of X, and then I collected another set of the data under a different condition (different temperature), and this has a different standard deviation Y. How do I cancel...

Homework Statement Suppose that 40 and 90 are two measurements of a population data set and that their z-scores are -2 and 3, respectively. Using only this information, is it possible to determine the population's mean and standard deviation? If so, find them. If not, explain why it's not...

Hi guys. Im new at this site so please be nice to me =P. I've been working on some practice papers for my upcoming end of semester exams. Cant get these two questions out ><. Any help is greatly appreciated Thanks in advance jenny xoxo 1. A sample of 28 students measured their...

hi all, i kind of have a black hole regarding my understanding of the consistensy of tidal forces and geodesic deviation analysis. one can determine some coefficients of the riemman tensor from the tidal forces equations, by getting to a form that is like the form of the geodesic deviation...

Hi, I'm just trying to find out if there is a calculation to that relates deviation from a straight line to the forward velocity and the rotation of a circular object. Essentially i have a small project that i get to prepare and work on and was thinking of trying to find the optimal bowling...

Given the mean energy of a system in a heat bath is \bar{E} = - \frac{\partial ln(Z)}{\partial \beta} Where Z is the partition function and \beta = k_BT Why is the standard deviation of E defined by: (\Delta E)^2 = \frac{\partial^2 ln(Z)}{\partial \beta ^2} I can't seem...

Standard deviation and mean - "combining" the two Lets say one was to have a range of data, with the mean and standard deviations for the different subsets of data. The "best" subset is that with the lowest mean, however how do I include the standard deviation when making my decision. For...

Homework Statement Problem 1.2 from the book Introduction to Quantum Mechanics (2e) by Griffiths: Suppose a rock is dropped off a cliff of height h. As it falls, a million photos are snapped, at random intervals. On each picture the distance the rock has fallen is measured. a) Find the...

This might be embarrasingly easy or impossible; I've been a computer programmer for too long since my statistics classes to tell for sure :blushing: I have a set of records with the following data for each record: interval, mean speed, standard deviation of speed, number of observations...

Hey i was wondering if anyone could help me with this question at all? I don't have a clue about the calculations and would be grateful if it could be explained to me! I'm really struggling! Thanks Some light emitting diodes are tested and a sample is found to have a mean lifetime of 2048...

but only knowing the previous standard deviation, the previous mean (and the sample to be removed). does anyone know how to do it?

Hi, How can I rigorously prove that the quantity S = \sum_{i=1}^{n}|X_{i} - a| (where X_{1},\ldots,X_{n} is a random sample and a is some real number) is minimum when a is the median of the X_{i}'s? Thanks.

Write a program to find and display the Largest, Smallest, Average, standard deviation and the Sum of all numbers entered from the keyboard.The data entry should end with a Sentinel Value. After finishing ask if the user wants to continue entering new set of numbers or not. , where X...

Hey guys, i have two question that me and a couple of my mates couldn't figure out for the life of us in class so i bring them here. The first one at first glance seemed fairly easy Homework Statement Calculate the angle of deviation at a glass air interface for an angle of incidence of...

In doing a problem, I considered N (a large number, in the range 100,000-1,000,000) raindrops, falling into A (fixed at 100) segments on a roof, distributed using a random number generator I programmed. In considering the number of raindrops that fell into a given segment, the average would be...

I ran across an interesting statistic today while doing some research, but it was stated as a matter of fact without explanation and there appears to be a dearth of material on it. It was stated that the Mean Absolute Deviation ("MAD") of a Normal (Gaussian) Distribution is .7979 of a Normal...