Calculating the mode of a distribution from the characteristic function

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Discussion Overview

The discussion revolves around the possibility of deriving the mode of a probability distribution from its characteristic function, particularly when the inverse Fourier transform cannot be analytically determined. Participants explore the implications of this limitation on the calculation of the mode.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions whether it is possible to derive the mode from the characteristic function, noting the challenge of finding the probability density function (pdf) through inverse Fourier transform.
  • Another participant expresses uncertainty, suggesting that the mode cannot be obtained but acknowledges that moments can be derived from the characteristic function through power series expansion.
  • A participant confirms the ability to compute moments such as mean, variance, skewness, and kurtosis, but highlights the absence of a clear method for calculating the mode.
  • Another participant proposes a method involving differentiation of the inverse Fourier transform, suggesting that the modes could correspond to zero-amplitude frequencies of a modified function involving the characteristic function.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the mode can be derived from the characteristic function, with multiple competing views and uncertainties expressed throughout the discussion.

Contextual Notes

There are limitations related to the assumptions on the pdf and characteristic function, as well as the unresolved nature of the mathematical steps involved in differentiating the inverse Fourier transform.

natski
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Is it possible to exactly derive the mode of a probability distribution if you have the characteristic function? I cannot get the pdf of the distribution because the inverse Fourier transform of the characteristic function cannot be found analytically.

Any thoughts would be appreciated!

natski
 
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Although I'm not absolutely certain, I'm pretty sure you can't get the mode. I presume you know that you can get the moments by expanding the char. funct. in a power series.
 
Yes, so I can compute the mean, variance, skewness, kurtosis... but I can't find an equation for computing the mode...

Natski
 
Hi Natski (found this old thread while looking for a solution to another problem)

To solve df/dx=0, what if you differentiate the inverse Fourier transform (with suitable assumptions on the pdf and c.f.) - if p(t) is the c.f. then the modes would be the zero-amplitude frequencies of (t*p(t)) ?
 

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