Re: Optimization of observations for the HST search

From: VAFadeyev@lbl.gov
Date: Mon Oct 20 2003 - 01:35:20 PDT

  • Next message: Ariel Goobar: "Re: Optimization of observations for the HST search"

    Ariel,

    This is what I see for z=1.2:

    Input stretch is 1.0 . The average fitted
    value from 25 simulations is 1.16 . There are
    two large positive outliers. After clipping
    the average becomes 1.04 .

    This suggests that if there is some bias,
    it may not be in the same direction as yours
    (on the plots you sent the average stretch < 1
    for z=1.2).

    The existence of the outliers is a bit worrisome;
    also, there are cases with abonormally small
    fit errors.

    vitaliy

    ----- Original Message -----
    From: VAFadeyev@lbl.gov
    Date: Monday, October 20, 2003 1:12 am
    Subject: Re: Optimization of observations for the HST search

    >
    >
    > Hi Ariel,
    >
    > it is good that the results are consistent.
    >
    > Your observation of the biases is very interesting. Was it ever
    > checked before that the LC parameter
    > extraction is self-consistent and bias-free, say
    > for lower redshift cases?
    >
    > The only reason why I switched off the randomization
    > was to save time. Otherwise I'd have to rerun
    > the code multiple times for every observation
    > sequence, derive the corresponding distributions etc.
    >
    > Initially I did briefly checked that with randomization turned on
    > there were no big biases
    > for z=1.3. This is close to your case of z=1.4,
    > where you don't have substantial biases either.
    > So perhaps this was not a very strict check.
    > Am rerunning that example for z=1.2 now. Will
    > report the results shortly.
    >
    > Cheers,
    > vitaliy
    >
    >



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