Re: [R] Fitting a distribution to peaks in histogram

From: hadley wickham <h.wickham_at_gmail.com>
Date: Thu 20 Jul 2006 - 05:27:53 EST

> Can you be a bit more excact? I a biologist and relatively new to R

In that case, I would _strongly_ advise that you get advice from a local statistician.

> I am measureing the amount of DNA in cells, and I need to know the
> percentage of cells in a part of the cell cycle; that the percentage
> of cells in the first peak, in the second peak and so on. I want to
> integrate the area between to two cells, because that apparently is
> how its none (as far as I can tell from the literature)

That doesn't sound quite right to me, because you also need to take into account the fact that some cells between peak 1 and 2 belong to peak 1, and some to peak 2. This is something that will come out immediately from a mixture based approach. If you know that peaks correspond to certain parts of the cell cycle, then this is important information that should be included in the analysis.

> It very probably is better, but mclust had no result after running for
> at least 2 hours (I terminated the function after two hours), and as I
> generate 50-100 datasets, such as the one used for the histogram, as
> week, I would like to find a faster solution

I doubt that mclust is appropriate for this task, so letting it run longer wouldn't help anyway.

Again I would suggest that you seek local statistical help.

Hadley



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