Re: ISIS: loading data with proper statistical error

I see, that's indeed a useful precision!

So the best way would be to add the ERR column in my PHA file and then start work on it with ISIS.

Thanks again,

Nicolas




Dr. Nicolas Barrière
***********************************************
barriere_at_email.domain.hidden510 - 643 - 4747
Space Sciences Lab
7 Gauss way
Berkeley – CA 94720
USA
***********************************************

On Nov 30, 2012, at 2:39 PM, Michael Nowak wrote:

> 
> On Nov 30, 2012, at 5:27 PM, Nicolas Barrière wrote:
> 
>>> 
>>> If your concern in your last question is whether in rebinning, errors are propagated by 
>>> something like adding quadrature, don't worry, they're not (unless you write that
>>> yourself).
>> 
>> Yes that was my concern. Thanks a lot for your clarifications.
> 
> I should also re-clarify that rebinning trumps get_data_counts/put_data_counts.
> So, if you create your own Gehrels statistic and use put_data_counts, and then rebin, 
> post-rebin errors will be replaced by whatever you've chosen via set_fit_statistic.
> 
> But I definitely do use put_data_counts.  In doing Power Spectral Densities, for 
> example, I first logarithmically bin the PSDs, and then set their errors as P(f)/sqrt(N),
> where N is the number of bins and P(f) is the bin averaged value of the PSD.  
> (That's the expectation for the error on a stochastic process.)  I just make sure
> not to rebin subsequently without redoing the put_data_counts.
> 
> Cheers,
> 
> Mike
> 

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