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  • dealing with sample sizes in logistic regression analysis


    I did a matched case control study in Uganda looking at Determinants of Severe malaria in Children (325 age-matched pairs; severe malaria cases vs. uncomplicated malaria controls). I am doing a sub-group analysis of risk factors by type of severe malaria syndrome; cerebral malaria (59 age-matched pairs) and severe malaria anemia (141 age-matched pairs).

    Using the clogit command I run a regression model for the cerebral malaria sub-group which resulted in some explanatory variables (EV) having OR with extremely wide CI. Based on the VIF scores, and the Conditional Index mullticollineraity doesn't seem to be a problem in the model. I therefore think the wide CI’s are attributable to small sample size numbers within the groups
    I've used to approaches to try and over overcome this challenge:

    1. Drop the EV; an undesired option for I lose the influence of the variable in the model.

    2. firthlogit command; and the problem appears to be addressed

    However, I am not sure if the firthlogit commands is applicable to matched data, and if not what are my options ?

    Thanks

    Arthur Mpimbaza
    Email: [email protected]

  • #2
    Arthur:
    welcome to the list.
    Please post your query on the General forum, as this one is conceived for practising only. Thanks.
    Kind regards,
    Carlo
    (Stata 18.0 SE)

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