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  • 1.  Difference Score as Outcome, Baseline as One of Several Covariates

    Posted 01-28-2022 09:10
    Dear Colleagues:

    Does anyone have any favorite articles that focus on the methodology of "change score from baseline" as outcome with baseline value as one covariate, along with demographics and others?

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    Brandy Sinco, BS, MA, MS
    Statistician Senior
    Michigan Medicine
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  • 2.  RE: Difference Score as Outcome, Baseline as One of Several Covariates

    Posted 01-31-2022 07:56

    If your interest is in issues with interpreting difference scores, I would search out these really old papers by Fred Lord. This topic has been around for a few decades - as I remember, the first paper concerns Lord's Paradox. I don't have copies, sorry. 

    Lord FM. A paradox in the interpretation of group comparisons. Psychological
    Bulletin 1967; 68: 304-305.
     Lord FM. Statistical adjustments when comparing pre-existing groups.
    Psychological Bulletin 1969; 72: 336-337.



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    Chauncey Dayton
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  • 3.  RE: Difference Score as Outcome, Baseline as One of Several Covariates

    Posted 01-31-2022 08:30
    I regard a good wide-ranging text to be:  Garrett Fitzmaurice, Nan M. Laird, James H. Ware. (2011). Applied Longitudinal Analysis (2nd ed.). Wiley. (ISBN: 978-0-470-38027-7). 

    The authors cover this topic in chapter 5, where they discuss four methods of handling baseline.  One of these methods uses "change score from baseline" as an outcome.  Another, uses the baseline value as a covariate.  The authors caution (in Section 5.7) that this latter method "should not be used … in observational studies where there is no a priori reason to assume that the groups have the same mean response at baseline."

     



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    David Thompson
    Emeritus Associate Professor
    University of Oklahoma Health Sciences Center
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  • 4.  RE: Difference Score as Outcome, Baseline as One of Several Covariates

    Posted 01-31-2022 09:05
    Yes, any article about the regression fallacy. The change = after – before  and baseline = before are correlated even if the before and after are independent. One account is in my article:

    The History of Statistics in 1933, Statistical Science, Vol. 11, No. 3 (Aug., 1996), pp. 244-252



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    Stephen Stigler
    The University of Chicago
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  • 5.  RE: Difference Score as Outcome, Baseline as One of Several Covariates

    Posted 01-31-2022 09:52
    If randomization was used to create the groups of analytic units for comparison of outcome then consider the following:

    Guanghan F. Liu∗,†, Kaifeng Lu, Robin Mogg, Madhuja Mallick and Devan V. Mehrotra: Should baseline be a covariate or dependent variable in analyses of
    change from baseline in clinical trials? Statist. Med. 2009; 28:2509–2530

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    Brent Blumenstein
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  • 6.  RE: Difference Score as Outcome, Baseline as One of Several Covariates

    Posted 01-31-2022 11:52
    Like a) Frison&Pocock 1992 StatMed for RCT or b) Tennant et al. 2021 IntJEpi for causality in observational data? As c) SEM by Kievit et al. 2018 DevelopmentCognitNeurosci? Or d) why marginal odds ratios are different from conditional odds ratios (Daniel et al. 2021 BiomJ)? a) and c) assume linear model. d) contrasts this with GLM.

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    Reinhard Vonthein
    Universitaet zu Luebeck
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  • 7.  RE: Difference Score as Outcome, Baseline as One of Several Covariates

    Posted 01-31-2022 16:39
    Senn, S. (2006). Change from baseline and analysis of covariance revisited. Stat Med, 25(24):4334–44.


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    Ralph O'Brien
    Professor of Biostatistics (officially retired; still keenly active)
    Case Western Reserve University
    http://rfuncs.weebly.com/about-ralph-obrien.html
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