Re: ISIS: loading data with proper statistical error

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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