# What is Fisher: Definition and 24 Discussions

Fisher Body was an automobile coachbuilder founded by the Fisher brothers in 1908 in Detroit, Michigan; it had been a division of General Motors for many years, but in 1984 was dissolved to form other General Motors divisions. Fisher & Company (originally Alloy Metal Products) continues to use the name. The name and its iconic "Body by Fisher" logo were well known to the public, as General Motors vehicles displayed a "Body by Fisher" emblem on their door sill plates until the mid-1990s.

View More On Wikipedia.org
1. ### A Computing the Fisher Matrix numerically

Hi, I have been studying the Fisher matrix to apply in a project. I understand how to compute a fisher matrix when you have a simple model for example which is linear in the model parameters (in that case the derivatives of the model with respect to the parameters are independent of the...
2. ### A Make cross-correlations between 2 Fisher or 2 Covariance matrices

I have 2 Fisher matrixes which represent information for the same variables (I mean columns/rows represent the same parameters in the 2 matrixes). Now I would like to make the cross-correlations synthesis of these 2 matrixes by applying for each parameter the well known formula (coming from...
3. ### I How to Get Final Fisher Matrix from 2 Matrices

I have 2 Fisher matrixes which represent information for the same variables (I mean columns/rows are the same in the 2 matrixes). Now I would like to make the cross synthesis of these 2 matrixes by applying for each parameter the well known formula (coming from Maximum Likelihood Estimator...
4. ### A Cross correlations with 2 probes: Approximation of a 2D + 3D synthesis

I am interested, in the context of my work, in the cross correlations between a spectroscopic probe (which gives a 3D distribution of galaxies with redshifts, which is also called spectroscopic Galaxy clustering, GCsp) and a photometric probe (which gives an angular distribution, that is to say...
5. ### A Why is the quantum Fisher information useful in quantum metrology?

I'm getting interested in quantum-enhanced metrology and have come across the quantum Fisher information (QFI) as a measure of how much a quantum state ##|\Psi(\theta)\rangle## changes with respect to some variable, for example, the phase accumulated during an interferometer, ##\theta##. This is...
6. ### A Forecast with Fisher formalism : loss or gain of information

In the context of a forecast, I am currently working on Fisher's formalism which is part of a more general theory, that of information. My problem applies to estimating cosmological parameters from input data with the Fisher formalism and recipes to build a Fisher matrix. The context is...
7. ### I Cross-correlations: what size to select for the matrix?

Hello, I am working on Fisher's formalism in order to get constraints on cosmological parameters. I am trying to do cross-correlation between 2 types of galaxy populations (LRG/ELG) into a total set of 3 types of population (BGS,LRG,ELG). From the following article...
8. ### I Fisher matrix - equivalence or not between sequences

I am currently studying Fisher's formalism as part of parameter estimation. From this documentation : They that Fisher matrix is the inverse matrix of the covariance matrix. Initially, one builds a matrix "full" that takes into account all the parameters. 1) Projection : We can then do...
9. ### Showing Rejection Region Equality with Fisher Distribution

Homework Statement [/B] For reference: Book: Mathematical Statistics with Applications, 7th Ed., by Wackerly, Mendenhall, and Scheaffer. Problem: 10.81 From two normal populations with respective variances ##\sigma_1^2## and ##\sigma_2^2##, we observe independent sample variances ##S_1^2## and...
10. ### A Zeros of the partition function (Yang-Lee and Fisher zeros)

Hey there, Just wondering where I can get a nice treatment of this with derivations. I could swear I read about this in Jon Cardy's Scaling and renormalization in statistical physics but I can't find it again so maybe I was wrong.
11. ### I What is the C_l in the Fisher Matrix For An CMB Survey?

I'm trying to construct a Fisher Forecast for the upcoming S4 CMB survey. I don't understand what the C_l is in this formula. It is H(z) and the Angular Distance? Or is it some covariance matrix and if it is a covariance matrix how do I calculate it considering the experiment hasn't been done...
12. ### A Fisher Forecasting For EUCLID Survey Help

I'm trying to recreate the results of this paper https://arxiv.org/pdf/1607.08016.pdf to obtain the constraints for the matter density and Hubble constant h. However every time I try to create there results my Fisher Matrix has elements of order of 10^14 which is far to high. I suspect this is...
13. ### A How To Do Fisher Forecasting For Constraining Parameters

I'm doing a Fisher Forecast to satisfy my experimental physics requirement. I never done anything like this before so I'm kind of in the dark of how to proceed. I have done some readings on Fisher Forecasting and would like to outline how I would do it and then ask if you can tell me if I'm...
14. ### News Carrie Fisher Dies at 60: Hollywood & Star Wars Icon

Carrie Fisher, Child of Hollywood and ‘Star Wars’ Royalty, Dies at 60 http://www.nytimes.com/2016/12/27/movies/carrie-fisher-dead-star-wars-princess-leia.html?_r=0
15. ### Carrie Fisher, Actress of Princess Leia, Dies at 60

More at http://www.rollingstone.com/movies/news/carrie-fisher-princess-leia-in-star-wars-dead-at-60-w457713 You will be missed, Carrie Fisher.
16. ### Maximum Likelihood and Fisher Information

Homework Statement Let X1, X2,...Xn be a random sample from pdf, f(x|θ) = θx-2 where 0 < θ ≤ x < ∞ Find the MLE of θMy attempt: Likelihood fxn: L(θ|x) = ∏θx-2 = θn∏ θx-2 And to find MLE, I take Log of that function and partial derivative (w.r.t θ, of log L(θ|x) and set that = 0, and get...
17. ### Mathematica Mathematica: Problem Computing Fisher Information of pdf

Hello, I'm trying to calculate Fisher information (and eventually the Cramer-Rao lower bound) for this particular pdf with Mathematica: \text{pte}[t,\Theta ] = \frac{P_{\text{ec}}}{\tau _d-\tau _r}\left[e^{\frac{-(t-\Theta )}{\tau _d}}-e^{\frac{-(t-\Theta )}{\tau _r}}\right]...
18. ### Fisher Information Matrix: Equivalent Expressions

I don't understand the following step regarding the (i,j)^{th} element of the Fisher Information Matrix, \textbf{J}: J_{ij}\triangleq\mathcal{E}\left\{ \frac{\partial}{\partial\theta_{i}}L_{\textbf{x}}(\textbf{θ})\frac{\partial}{\partial\theta_{j}} L_{\mathbf{x}}(\textbf{θ})\right\} \\...
19. ### [Quantum Mechanics] Quantum Fisher Information for a Pure State

Hi everyone. Homework Statement We are given N spins 1/2. A rotation is defined as \rho_\theta=e^{-i\theta J_n}\rho_\theta e^{i\theta J_n} on an Hilbert Space H, with J_n=n_xJ_x+n_yJ_y+n_zJ_z\:,\quad n_x^2+n_y^2+n_z^2=1, and \theta isn't related to any observable. Given a quantum state...
20. ### How to understand fisher information ?

How to understand "fisher information"? Hello, I am trying to understand what "fisher information is." It is defined as V [∂/∂∅(lnf(X,∅)) ]=E[ (∂/∂∅[lnf(X,∅)])^2 ]. From Wikipedia: Can you please help me understand why this is the case? How can this be explained by looking at the...
21. ### Invariance of the Fisher matrix

Fisher matrix=(minus the) average of the second derivative of the log-likelihood with respect to the parameters It seems to me the Fisher matrix for Gaussian data is invariant with respect to any (non-singular) linear transformation of the data; if correct this is a very useful property...
22. ### Fisher matrix for multivariate normal distribution

The fisher information matrix for multivariate normal distribution is said at many places to be simplified as: \mathcal{I}_{m,n} = \frac{\partial \mu^\mathrm{T}}{\partial \theta_m} \Sigma^{-1} \frac{\partial \mu}{\partial \theta_n}.\ even on...
23. ### Understanding Fisher Information: Visualizations & Explanations

Maybe it is a good idea to have mathematical tutorials like in the subforum about Physics. I have no homework anymore :smile: but tend to think that doing mathematics is a skill that always pays back at the end. First thing I want to know what https://en.wikipedia.org/wiki/Fisher_information...
24. ### Science from Fisher information

Have some of you read this book by Roy Friedel? What are your comment? I am also interrested in other sources about "information" and "Fisher information" as it could be used in physics. Thanks Michel