# Tagged Questions

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### How to combine two fitted variables

I have fitted two (and probably more) sets of data to a model using least-squares regression. So I've got the parameter values together with their errors and a reduced chi-squared for both. The data ...
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### How to combine the chi-square distributions (with one model parameter) of many items in a sample?

I have a sample of items, for each of which I have fitted models to obtain the best-fitting ($\chi^2$-minimising) value of a parameter $\alpha$. So for each, I have the values of $\chi^2_i(\alpha)$ ...
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I have an extremely simple question regarding chi-square test. So far I have found two different formulas for it: $$\chi^2=\sum\frac{(x_o-x_e)^2}{x_e}$$ and $$... 1answer 294 views ### Efficient fitting of noncentral chi-squared distribution to data? I am looking for the most efficient way to fit a noncentral chi-squared distribution with fixed d.o.f. to a given data set. So the inputs are d.o.f. and the data and the output should be the ... 1answer 813 views ### \chi^2 fitting with correlated errors I have been doing some fitting using the fairly standard expression,$$\chi^2 = \sum_i \frac{(y_{i} - F(x_{i}, \theta))^2}{\sigma_{i}^{2}} where y is my measured data, $\sigma$ is the experimental ...
Suppose I have a set of $N$ experimental points of the form $$\{x_i, y_i, d_i\},$$ where $i=1,...,N,$ and $d_i$ are errorbars for $y_i$. To fit the data, I minimize the ...