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Use this tag for any use of optimization within statistics.
4
votes
1
answer
96
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What is the solution to this minimization problem?
I'm encountering the following minimization problem in my research:
$$\hat b = \underset{b}{\arg\min} \sum_i^n \left( \log \frac{a_i}{b} \right)^2$$
I could iteratively optimize, but I think that th …
4
votes
2
answers
1k
views
Optimizing $\chi^2$ using MCMC
I have measurements of an object.
Let's say I have its length $L$, mass $M$, and age $t$: $$\mathbf y = (10~\text{m},\ 0.01~\text{g},\ 5~\text{s}).$$ I also have the uncertainties on my measurements …
3
votes
0
answers
445
views
Optimization with/without an analytical gradient
A colleague is optimizing a function (e.g. trying to find the minimum of a function $f(x_1, x_2, \ldots)$). We know the analytical form and it is differentiable. I suggested calculating the derivative …
3
votes
1
answer
195
views
Likelihood convexification
I am doing constrained vector optimization using a non-convex non-linear likelihood function. …
3
votes
1
answer
959
views
How to find $\arg\max$ of a neural network?
Let's say I have a neural network $f$ that takes input $\vec x \in \mathbb {R}^n$ and produces output $f(\vec x) \in \mathbb{R}$.
How can I find $\hat x = \underset{\vec x}{\arg\max} \; f(\vec x)$?
2
votes
0
answers
23
views
Measuring goodness of fit when making a localized average of a function with uncertainty in ...
Another worry is the fact that the $\sigma$s depend on $\vec \alpha$, and so this optimization procedure may choose to inflate $\sigma_x$ and $\sigma_y$ instead of getting good estimates $x_0'$ and $y_ …
2
votes
1
answer
268
views
Linear regression of B-splines with terms inside an integral?
I have encountered a problem that the literature suggests linear regression is able to solve, but I am at a loss.
I have a function $F$ that I want to estimate. This function obeys $N$ equations of …
1
vote
0
answers
42
views
Determining the objective function for a non-linear minimization problem
I have observed a vector of quantities $\vec y$. I wish to use these to constrain a vector of initial conditions $\vec x$ that are related to $\vec y$ through a non-linear (numerically evaluated) func …
1
vote
0
answers
81
views
How to propagate "model covariance" into a covariance matrix?
I have a theory $f$ (actually a set of coupled non-linear differential equations) that, from a vector of $n$ initial conditions $\vec x$, is able to predict $m$ values $f(\vec x) = \vec y$.
I can me …
1
vote
Accepted
Optimizing $\chi^2$ using MCMC
This paper gives an answer. The answer is in order to minimize $\chi^2$, one can maximize a log likelihood function $-\chi^2/2$.