Recent content by aymer

I already have an mcmc chain of parameter values and corresponding chi-square values. I have not used cosmomc though. Can you give me an idea how are the confidence regions estimated from the chain?

Hello.. I am dealing with a cosmological parameter estimation problem. I have a sum of squares function (chi-squared) of two parameters and I have minimized it using fminsearch, to find the best fit. Now, I want to plot 1-sigma, 2-sigma confidence contours for this. My parameter probability...

The data is a vector of observed values at different z's. All the three data vectors i.e data.xdata, data.ydata and data.zdata are 32X1 matrices

Homework Statement I am using MATLAB to minimize a sum of squares (chi-squared) function. My model has a definite integral (from zero to data values).The model has three parameters w.r.t which I need to minimize. [b]2. relevant equations *I need to integrate (1+x).^(b-a-2).* exp(-b.*x) from...

Its strange that nobody replied to this...I just want a reference as to wherever an attempt was made to derive the relation in a model/background independent way...i tried reading the Etherington paper (he was the first to introduce it I guess) but its a bit too technical for me...

Hi , I need help from someone who has worked out the distance duality relation (between angular diameter distance and the luminosity distance).I am having trouble deriving it and the Etherington paper is a bit too tough for me where it was first discussed (1933). In one of the reviews its...

Thanx, So I guess what i have done is correct and the authors of the paper must have just scaled the graph to one somehow.I was worried because I was getting the peak at the same point and my graph intersects the x-axis at the same coordinates as the paper.

i also tried normalizing each event(i have 17 data points) to 1 and find corresponding normalization constants. Then i plotted (product of constants)*exp[-chisquared/2],but even that is not scaled to 1.

hii, i tried doing the normalization as you suggested by doing [A*integral(exp[-chisquared/2])] over the parameter(-inf,inf) and equated it to 1 to calculate A. then i plotted A*exp[-chisquared/2] vs the parameter. but still it is not normalized to 1. the maximum value the function takes is...

Hi there, Thanx for the response. I am using the statistical software R

Thanx, I thought of integrating the likelihood and equating it to find the normalization constant but the problem is my chi-squared itself is a function of an unknown parameter,the value of which I want to find. So we have two unknowns-the parameter and the normalization constant and only one...

Hey everyone, This is for someone who has used R. Please tell me how can we sum a function with a free parameter in R. I used the normal command f=function(n) sum(body of function containing n) it does not show any warnings till here, but when I plot this sum vs n (which i now define as a...

Hey everyone, i am new to using statistics and have come across a problem. I am trying to regenerate the result of a paper in which a theoretical parameter is constrained. I have calculated the chi squared and plotted the likelihood function (exp[-chisquared])to see what value of the...

hi there we know that electrons around the nucleus in an atom can only exist in certain discrete energy levels (orbits) and that they can jump from one energy state to a higher one or a lower one. where is the electron when it is jumping from a higher stste to a lower state if it cannot exist...