Correlation Definition and 370 Threads

Given two entangled particles, and the spin of both is measured along two separate axes making an angle of "a", what is the correlation between the two? So how much of the particles will give the same "answer" to the spin measurement? I've tried googling, but the answers I did find were...

I am unsure of this matter and so I am curious, do stronger metals more than likely have higher melting/heating points? Does a metal that takes more force/pressure to break or snap have a higher melting/heating point as well? Do metals/alloys like steel or titanium have higher melting points...

Spatial Cross Correlation help urgently needed! I am working on Cross Correlation at the moment with varying degrees of success. I have figured out how to do Cross and Auto Correlation but am lost tryng to understand spatial CC. I can't seem to find any helpful resources for what I am working...

I want to know how one might calculate the cross correlation of two signals by hand. I know that there are a myriad of software applications that will do this for me but I want to understand how it is done by hand. I'm using the expression: ccxy[k] = ∑ x[n]. y[n+k] I'm just not too sure what the...

From my understanding the job of a theoretical physicist is to derive theories to explain phenomena in nature. But let's say you aren't the best problem solver in the world. You are good enough in your physics class to get the 3.5 GPA but you are never able to solve those extra credit problems...

Hi all, I would like some help understand the covariance and correlation matrix as it pertains to estimated parameters. I am performing logistic regression with just one independent variable and a constant term. I am wondering if someone can help me understand the information these...

Hy. I have a problem about correlation depending whether it it observed as a measurement of linear fit of statistical data, and when observed as a relationship between two continuous functions. Is a result of correlation a coefficient (Pearson's product-moment coefficient) or a function...

If I have three scalar random variables: a, b and c, which are each zero-mean and have some nonzero variances, and I know: 1) The correlation between a and b is nonzero. 2) The correlation between b and c is nonzero. Does this imply that the correlation between a and c is nonzero? I...

The Correlation.. !?? Homework Statement Bert and Ernie are trying to impress Lady Moneypenny with their surfing skills. Bert’s wave ride times are normally distributed with a mean of 15 seconds and a standard deviation of three seconds. Ernie spends more time drinking rather than...

Hello everyone, My boss has asked me to find if there is any correlation between various sample parameters in a water quality study. We took around 150 samples, and for each one measured around 50 parameters e.g. iron content, free residual chlorine, level of coliforms, pH, etc etc. I...

Hi I have two images and I want to compare the "structures" of them at different scales. I remember from cosmology that the two point correlation function was used to extract similar structural information from the CMB, generating a graph of structure Vs scale. Then at certain length scales you...

Hello everyone, I have a question.. if I have a data stream X=some thousand random numbers with mean close to 0 and standard deviation close to 1 and then I construct my autocorrelation matrix from these numbers Q=|R_xx{0} R_xx{1}...R_xx{L}| | R_xx{1} R_xx{0} ...R_xx{L-1}|...

Try predicting the news a week ahead of time! Just cite a source for the current state of the news and make a significant prophecy about it -- physical, informational, sporting, political, academic, etc. Just place this "gentleman's bet" here, a week before the augured event. It's you...

After reading so many threads here about it, I thought I would take a closer look at Bell's theorem. Consider the simple proof presented http://quantumtantra.com/bell2.html" , which I'll summarize below: A light source produces twin state photons, and each photon of the pair goes through a...

I found a claim in a paper (BSSA, Vol 81, No. 6: "A Waveform Correlation Method for Identifying Quarry Explosions", By D.B. Harris) concerning finding filter coefficients. The statement is given without proof. I cannot locate a reference or theorem for the following, and have not been able thus...

Please teach me this: In QTF theory of Schroeder,chapter 13.1 saying: Just at t=0(t=\frac{T-T_{c}}{T_{c}}),the correlation should decay as power law. Define the exponent \eta by the formula: G(x)=\frac{1}{x^{d-2+\eta}} where d is Euclidien space dimension. I do not understand why at...

Hi, Why there is a half factor in the definition of the correlation of complex random variables, like: \phi_{zz}(\tau)=\frac{1}{2}\mathbf{E}\left[z^*(t+\tau)z(t)\right]? Thanks in advance

Hi. Can somebody recommend a good book (advanced level) dealing with applications of cross correlation functions? I mean what kind of conclusions can be drawn etc?

Homework Statement The correlation coefficient for each of two data sets is calculated. Set A has r = -0.75 while Set B has r = +0.55. Which set (A or B) has the stronger strength of relationship? Homework Equations I think -0.75? The Attempt at a Solution I think Set A r =...

It is often said that QM is not truly nonlocal, because the "only" thing which is nonlocal are the correlations; there is no true nonlocal causation involved. At the same time, the Bohmian interpretation is accused for being "too" nonlocal, by involving a true nonlocal causation. But what...

I’ve seen much confusion here concerning the difference between instant correlation at a distance and instant “communication”, or transfer of information at a distance, and a simple thought experiment can clarify the difference. In Experiment A, we stick two coins together, one heads up and...

Please teach me this: Why the connected correlation functions depend on the x-y(the difference of two space-time coordinates of two points) only in case the expectation of field(<phi(x)>) is constant(the translation invariance of vacuum state). Thank you very much in advanced.

How can I find the correlation length of an auto-correlation? Is it the distance to the first zero of the auto-correlation? Is it the distance to the first min. of the auto-correlation? Is it the distance to the first max. of the auto-correlation? or should I integrate? Thank you

Do we need a coincidence counter (for correlation) in delayed erasure?...in case of repeating the same experiment many times (with one photon at a time) the same way In the DCQE experiment such as the one listed below http://grad.physics.sunysb.edu/~amarch/ Notice the polarizer...

So we have the definition of the correlation (or Green's) function as G^{(n)}(x_1, \dots , x_n) = \langle \Omega | \phi(x_1) \dots \phi(x_n) | \Omega \rangle Now I need to show that they are Lorentz invariant i.e. that G^{(n)}(x_1',\dots,x_n')=G^{(n)}(x_1, \dots , x_n) However, we know...

hi, i want to learn about exponentially correlated random functions. can some one help me with some ideas or links or books. thanks in advance.

Hi all, I read on some paper that for a system of Fock state |...nk...>, and with the field operator expanded as \Psi(r)=\sumak \phik(r), the second order density correlation function can be expressed as G(2)=<\Psi+(r)\Psi+(r')\Psi(r')\Psi(r)>=<n(r)><n(r')>+|<\Psi(r)+\Psi(r')>|2-\sum^{N}_{k}...

Please teach me this: Why 2-point correlation function diagrams have only two external lines.Because of Wick theorem they would have many external legs. Another thing is whether are there odd number point correlation functions(meaning they are different from 0). Thank you very much in advanced.

Homework Statement The Fourier transform of the auto correlation function is the energy spectral density (ESD) of a signal. Here is the "apparent" proof: \int e^{-jwT} [ \int g(t)g(t+T)dt] dT => \int g(t)[ \int g(T+t)e^{-jwT}dT] dt What happened here? Why did the second integral change from...

Should one view correlation functions as: (1) \; \langle T{\phi(x)\phi(y)}\rangle or (2) \; \langle T{\phi(x)\phi(y)}\rangle - \langle \phi(x)\rangle \langle\phi(y)}\rangle with the second term being zero? (2) makes more sense as it really measures whether the two fields are...

Homework Statement I have two equations: \frac{\partial}{\partial z}E_{L}\left(z,\omega \right) = i \frac{2 \mu d_{eff}(\omega+\omega_{0})^{2}}{k(\omega+\omega_{0})}\int E_{L}(z,\omega-\omega_{T})E_{T}(z,\omega_{T})d\omega_{T} \frac{\partial}{\partial z}E_{T}\left(z,\omega_{T} \right) = i...

I have a 2-dimensional field of values (they are actually heights of a surface) and I want to compute a correlation function or some sort of correlation parameter. I have seen something similar done with galaxies and you end up with something like the probability of finding a galaxy at a...

Hi all, I have run a few linear regression models predicting water quality for watersheds using explanatory variables such as mean impervious surface within watersheds and others suggested by theory and the research of others. I would like to be able to compare explanatory variables measured...

why is the redshift space correlation function smaller than the realspace correlation function at small scales and the opposite on large scales?

Hi! I need to write MATLAB script, which will be plotting corretation function for two-dimmensial system. Henon map is not my system, but is very popular, so solusion for henon map can be very helpful for me. Have anybody know code for have plot like this...

Science quiz question: How to determine the correlation between a car’s horsepower / torque and the maximum break strength of a cable that will hold the motor stationery. Assuming that the wheels of a car do not spin, how can I determine what the required cable’s break strength needs to be...

Hii, I was wondering whether there is any correlation between the energy eigenvalues of a single atom (say He) with the electronic band structure of a collection of He atoms. for example, for He atoms the lowest energy would be the ground state, with 2 electrons. So will the lowest band for a...

Hello all, I am currently building a model in Excel for predicting domestic water demand on a daily basis. The daily model will be compared to a more accurate model which runs on timesteps of 5 minutes (the latter is data intensive however which is why we are building a daily model as it...

Hi, everyone: I have been curious for a while about the similarity between the correlation function and an inner-product: Both take a pair of objects and spit out a number between -1 and 1, so it seems we could define a notion of orthogonality in a space of random variables, so...

Hi, I have a problem in calculating the second order correlation (coherence) from the master equation for the operators \sigma and a a[+][/SUP] , because I don't know if <aa^{+}a^{+}a> can be factorized to<a><n><a>. I want to do this calculation directly from the density matrix solution. thanks

I'm trying to prove that abs(r) <= 1. (Ill apologize up front that I am not sure on how to write all equations properly in this forum, but Ill try to make it clear) Note that this is all sample statistics, not population, which is why I'm using r and not rho. I know that I have to use...

I wonder, what the physical meaning to electron correlation in molecular systems? and. Is there many types of it? Thanks for interest colleagues

Hi, I am going through Non Equilibrium Statistical Mechanics by Zwanzig and I can't follow, the step below: I have the equation: <x^{2}> = \int^{t}_{0}ds_{1}\int^{t}_{0}ds_{2}<v(s_{1})v(s_{2})> I can't show that: \frac{\partial <x^{2}>}{\partial t} = 2 \int^{t}_{0}ds<v(s)v(t)>...

The thing I don't understand is how does finding out the median help you drawing in the horizontal and vertical lines. How do you know if it's going to pass through a few of the data points? Like in the example on that website it has a moderate negative correlation and the median is the 8'th...

I am writing a paper publishing scientific data. My background is chemistry but I have taken a couple of stat classes. In my opinion, one of the biggest deficiencies in modern research publications is the improper use of statistics. I hope to avoid making this mistake, but I need your help...

So there was a thread: https://www.physicsforums.com/showthread.php?p=2847138#post2847138 about IQ and being successful that I think is an interesting topic and is worthy of discussion so I thought I'd start a new thread here. The reason for doing so is that I was recently reading Malcolm...

I have the following problem: Suppose there is a survey of persons with two properties each (a and b). a can take a relatively small number of values (say the political inclination: Conservative, Liberal, Socialist, or Other) the other one b can take a large number of values (say: the country...

Hi, Does anyone know if there's a closed formula for the n-point function in a CFT? Up to anharmonic ratios, of course. Most books just have it up until n=4. Thanks, Matt

Hi guys, I have data of 20 peoples height, weight, calorie intake and skinfold thickness. I have carried out a regression of calorie on height, on weight and on height and weight. I have done the same thing for skinfold thickness. I then used R to work out the summary of results. each...

I've been looking at some of the more prestigious graduate programs in physics and I've noticed in photographs that all of the grad students look very young. On the Princeton website, I couldn't spot one that looked over 25. Is it fair to say that more prestigious institutions tend to avoid...