Correlation Definition and 338 Threads

I'm stuck on this problem: Let X be uniform[0,1] and Y be uniform[0,X]. Calculate the covariance and correlation between X and Y. thanks

Hello, First time post long time lurker! I've got an interesting project I am working on which involves a few MechE subjects. The overall goal (for now) is to determine the drag force of a cylindrical cone headed object in sand under various pressures. The movement of the cylinder is the tricky...

Homework Statement Let X be a random vairable which can only take three values: -1,0,1 and they each have the same probability. Let Y also be a random vairable defined by Y = X2. Show that i) X and Y are not independent ii) X and Y are uncorrelated Homework Equations To show that two...

I would appreciate some help with this problem. Assuming X and Y are independent, I'm trying to find the correlation between XY and Y in terms of the means and standard deviations of X and Y. I'm not sure how to simplify cov(XY,Y)=E(XYY)-E(XY)E(Y) =E(XY^2)-E(X)E(Y)^2. If X and Y are...

I would appreciate some help with this problem. Assuming X and Y are independent, I'm trying to find the correlation between XY and Y in terms of the means and standard deviations of X and Y. I'm not sure how to simplify cov(XY,Y)=E(XYY)-E(XY)E(Y) =E(XY^2)-E(X)E(Y)^2. If X and Y are...

What are the general properties of 3-point correlation function of a spin-2 field? And what about 4-point, 5-point correlation functions? spin-3, spin-4 fields? What mathematical category do these problems belong to? Are there any specific studies on them? (They are so widely used in...

I had a question on a test this past friday that left me absolutely scratching my head. "The greater the density of a liquid the greater its ...?" 1 volume 2 area 3 viscosity 4 buoyancy While viscosity seems like the best option, this question was for a piping/plumbing test, and...

the correlation between A and B is 0.8 and between B and C is 0.9. I have to calculate what the least correlation A and C can be. \begin{pmatrix} 1 & 0.8 & x\\ 0.8 & 1 & 0.9\\ x & 0.9 & 1 \end{pmatrix} using sthe standard equation for eigenvalues you get...

When dealing with system containing millions of particles( for example, charged particles or magnetic particles) with statistical mechanics, I may often see the description or explanation that the certain effect is due to the coupling or correlation of particles. So can anybody give me a...

Hello All, I just read in a book that springs are pretty much analogous to capacitors in terms of energy considerations to capacitors. For eg. If a mass m suspended by a spring comes to rest after downward displacement y, Assuming compression = y for equilibrium, mg=ky thus k = mg/y...

How to do correlation using a set of data?

Is it generally true that the ground state of a given quantum system corresponds to the lowest quantum numbers? If so, how do we know this?

Homework Statement I have have a set of data pairs (x, y); (1, a) (2, b) (3, c) (4, d) (5, e) (6, f) (7, g) The least squares regression line for the this set is y=3x-12 Determine the new gradient of this line if the original set of scores has been transformed to; (6, a+3)...

I wasn't sure where precisely to put this, hopefully it gets an answer here. In my computational physics class we just learned about the correlation dimension. I know how to compute it, but don't quite know what it means. I learned roughly that the correlation dimension of something is a...

I am going through some of the problems in a statistical physics book. I am stuck on the following question: If we have two random variables X and Y, related by Y=mX + b => y(i) = mx(i) + b, where b and m are deterministic, prove that corr(X,Y) = m/sqrt(m^2) = sgn(m), where sgn(m) is the...

[SOLVED] Help with variance sum + correlation coefficient formula This is a worked example The objective is to prove -1 \leq \rho(X,Y) \leq 1 Then the book uses this formula... (2) 0 \leq Var(\left \frac{X}{\sigma_x} + \frac{Y}{\sigma_y} \right) (3) = \frac{Var(X)}{{\sigma_x}^2} +...

1. A system of 7 objects each have one measurement taken of them. These measurements are to be compared with two theoretical models, which theoretical model does the data fit best?[br]The machine used to measure the values has an extremely small error, so the data gathered does not have...

Homework Statement A signal x(t) is transmitted and received back as y(t) and sampled in the receiver, so we get a DT signal y[n] = ax[n-D] + w[n], where w[n] is noise baiscally i need to explain how we can measure the time delay by computing crosscorrelation Ryx(l). My undestanding is...

Homework Statement This is a question from an exam in fractals and chaos. The paper is attached, the question is the first one, part (b). Homework Equations In the paper The Attempt at a Solution Am I expected to compute continuous correlation functions with respect to epsilon...

Hi I am i new member, i hope i am posting in the correct forum. I require some help i with a problem i am trying to solve in my work. Currently we have 3 separate leak test methods specified for a part all with different working gases and pressures. If possible, i would like to correlate this...

Homework Statement 1D polymer, fixed segment length a If the angle between segment j and j+1 is 0, the energy is 0 If the angle is pi the energy is +2J. Compute the correlation function <s_i s_{i+n}>, where s_j = \pm 1 denotes the direction of segment j Find the persistence length Lp...

Wire "Creeping" Thin wires tend to creep (extend longer over periods of time), particulary at high temperatures. Is there a "formula" that explains this correlation of the amount of creeping with regards to temperature or other factors?

Could some one please help me with the following question. The ages and salaries (in thousands of $) of 10 employees in a firm are given below. Age - Salary 28 - 17 31 - 22 31 - 28 35 - 20 40 - 26 44 - 30 45 - 32 48 - 18 53 - 33 67 - 42 What is the...

Hi, Here's my question: Determine the correlation coefficient of the random variables X and Y if var(X)=4 and Var(Y)=2 and var(X+2Y)=15 I said let Z=X+2Y and then Var(Z)=E[Z^2]-E[Z]^2 Then I multiplied the thing out: 15=Var(z)=E[X^2]+4E[XY]+4E[Y^2]-E[X]-2E[Y] I know that...

I am trying to find a pattern between male and female concerns in this survey.

Hi, I was just wondering about spearman's rank correlation coefficient hypothesis tests - for these to be valid does the data in the sample have to be drawn from a bivariate normal distribution or does that only apply to the product moment correlation coefficient? Cheers, Just some guy

The question basically states write a brief overview of the correlation between the properties and uses for copper, iron, aluminium and zinc. Now I know this sounds like a simple research task, it's supposed to relate to periodic trends and their placing on the table. It's in this area that...

A computer program, MicroLab, deals with finding the best fit curve, or allowing for linear regression of the first, second, and third orders, of a given set of data (particularly modeling nonlinear data). I am trying to stimulate this analysis on a graphing calculator (i.e., TI-83 Plus and...

Hello All, I am trying to look at some correlation numbers and while I am aware that correlation does not always indicate causality can a correlation coeffiecent that is very near to zero be used to indicate that it is not a cause? Thanks C

In a sample of 21 observations obtained it was found that sales and price have an inverse relationship and coefficient of determination is 106% as much as the adjusted coefficient of determination. It is also known that the variance of sales around mean is 640. What is the coefficient of...

Hi all. Suppose I am increasing the flow rate of the water through a sprinkler or a tube, there should be some vibration induced by this increment of flow rate, right? On the other hand, if I decrease the flow rate of the water through the same sprinker, there should also be vibration induced...

This is the equation for the Rank Correlation Coefficient: 1- \frac {6 \sum d^2} {n(n^2-1)} can anyone explain the 6? why a six? i don't see the link.

Now how exactly did Pearson derive his correlation coefficient?

Hi, Have just been reading a paper which talks about a 'height-height correlation function' of a surface. Doesn't provide any equations, but as far as I can make out it seems to be a way of reducing the topography of the surface to a small number of characteristic parameters, which makes sense...

Hi, I'm having problems with this quantum mechanics problem. This is from a practice final I found online somewhere. A particle of spin S has either spin S=0 or spin S=1. It decays into two electrons, and the spin of the two electrons is that of the original particle. The electrons come out...

When you move through space time slows down, this is part of special relativity right. Hence when Light is moving at 670 million miles a hour time stops, and if you were to try and fly a spacecraft at 335 million miles an hour time would slow down by 1/2. But what I want to know is, since we...

Do polarization cross-sections from opposite microwave background n-poles disobey the Bell inequality?

I have got a bit of problem here. I have got 4 sets of results for a biology experiment, and I want to find the correlation between them. So I read about Spearman's rank coefficient but it only works for two sets of results. Can somebody help please?