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BOOTSTRAP_MEDIAN

BOOTSTRAP_MEDIAN

Name


    BOOTSTRAP_MEDIAN

Purpose


    Calculates the median and a confidence limit on the median based on
    bootstrap resampling.

Category


    Math

Calling Sequence


    Result = BOOTSTRAP_MEDIAN(Values)

Inputs


    Values: A vector of values whose median and error is to be calculated.

Keyword Parameters


    NBOOT: Number of bootstrap resamplings. Default: 1000.
    CONFLIMIT: Confidence limit. Default: 0.68 (equivalent to 1sigma
                for a normal distribution).
    UNIQLIST: If independent points are associated with more than one
                element of Values, then they should all be included or
                excluded together in the bootstrap resampling. In this
                case, set UNIQLIST to the result of running UNIQ on
                a list with the same length as Values containing the
                unique identifier associated with each. Note that for
                this to work, Values must be sorted in order of the
                identifier.

Outputs


    Returns a 3-element vector containing the lower limit, median, and
    upper limit.

Example


    Calculates the error in the median of 5000 values distributed normally:
    IDL> vals = 2.5*RANDOMN(seed,5000)
    IDL> PRINT, BOOTSTRAP_MEDIAN(vals)
        -0.25968859 -0.15505694 0.095240064

Modification History


    Written by: Jeremy Bailin
    12 June 2008 Public release in JBIU



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