• Re: How to construct normal reference values using spss?

    From Kuenzang Dorji@21:1/5 to m.ro...@student.rug.nl on Wed Oct 6 00:06:57 2021
    On Tuesday, November 6, 2018 at 7:10:41 PM UTC+6, m.ro...@student.rug.nl wrote:
    Tha ta poume sto spiti
    Can I know the name of the article? the link is not working. Thanks

    --








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  • From Rich Ulrich@21:1/5 to kuenzangd@health.gov.bt on Thu Oct 7 14:24:01 2021
    On Wed, 6 Oct 2021 00:06:57 -0700 (PDT), Kuenzang Dorji <kuenzangd@health.gov.bt> wrote:

    On Tuesday, November 6, 2018 at 7:10:41 PM UTC+6, m.ro...@student.rug.nl wrote:
    Tha ta poume sto spiti
    Can I know the name of the article? the link is not working. Thanks

    Here is the message starting the topic, which you failed to
    include with the question. I found this by looking at the
    "references" in your header. It is not very helpful.
    = = = start
    I have been trying to construct normal reference values for a
    biometric fetal parameter but after finishing this process, the
    equations for the median and the standard deviation do not seem to fit
    with the values when I run these equations to look for the normal
    distribution.
    The statistical method to estimate reference intervals was the one
    described by Royston and Wright.
    Do you know (step by step) how to construct normal reference values
    using spss?
    Thanks for your help !!!
    = = = end

    When I Google on most of the Subject, I also find this
    further (original) response, which may be the article
    you ask about, and which you should have quoted with
    your question.

    = = = start
    First, I recomment software Medcalc (www.medcalc.be), it calculates
    reference intervals using parametric and non-parametric methods.
    Furthermore, it calculates CONFIDENCE INTERVALS of estimates for
    reference limits.

    You get meaningful reference values, if you might have a sample size
    of at least 120 subjects (see CLSI guideline C28-4).

    In SPSS, you could calculate 2.5% + 97.5% percentiles,or other
    percentiles (95%), using -->analyze --> frequency --> statistics.

    FREQUENCIES
    VARIABLES=M4.1 /FORMAT=NOTABLE
    /PERCENTILES= 95
    /ORDER= ANALYSIS .

    However, there are a lot of possibilities how to estimate a percentile
    with SPSS (Default is waverage, ...).
    Search for "Methods for computing percentiles" within Google, and look
    at the MedStats-entry. Here, several options how to calculate
    percentiles are discussed.

    And: the CI of reference limits are not given in SPSS.

    The free available paper describes calculation of CI:
    Campbell MJ, Gardner MJ (1988): Calculating confidence intervals for
    some non-parametric analyses. British Medical Journal, 296, 1454-1456 http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1833334&blobtype=pdf

    Best regards
    Thomas Keller
    ACOMED statistik
    = = = end

    Yeah, that nih link did not work. Shortening it did not help (which
    sometimes does help).

    When I Googled on much of the title of the paper, I found https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2545906/

    - which seems to be the right reference.

    Google can be your friend.

    --
    Rich Ulrich

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