Advanced Search
MyIDEAS: Login to save this paper or follow this series

Case-control study power and sample size calculations using Stata

Contents:

Author Info

  • Katie Saunders

    ()
    (Cancer Research UK, Genetic Epidemiology Division, University of Leeds)

  • Tim Bishop

    (Cancer Research UK, Genetic Epidemiology Division, University of Leeds)

  • Jenny Barrett

    (Cancer Research UK, Genetic Epidemiology Division, University of Leeds)

Registered author(s):

    Abstract

    We use Stata's npnchi2 and nchi2 functions to calculated power and required sample size for case-control studies. Following the method described by Self et al (1992) a large exemplary data set with expected risk factor frequencies among cases and controls under any alternative hypothesis is created. The likelihood ratio test statistic for the hypothesis of interest is distributed as a non-central chi-squared statistic under the alternative hypothesis, and the likelihood ratio test statistic from the analysis of the exemplary data set is an approximation to the non-centrality parameter for this distribution. We apply these methods to power and sample-size calculations for case-control studies of gene-gene and gene-environment interactions. Because of the low power of case-control studies to detect interactions, a wide range of different strategies have been proposed. Required sample size depends on several design parameters and so the simplicity of these methods means that the efficiency of many designs can be compared over different ranges, a valuable tool at the planning stage of a study. Results are presented for population based, family and matching schemes that have been proposed to improve power, and comparisons of the power of different designs are made. Stata programs are available for these comparisons.

    Download Info

    If you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.
    File URL: http://fmwww.bc.edu/repec/nasug2003/talk4.ppt.zip
    Download Restriction: no

    File URL: http://fmwww.bc.edu/repec/nasug2003/saunders.zip
    Download Restriction: no

    File URL: http://cruk.leeds.ac.uk/katie
    Download Restriction: no

    Bibliographic Info

    Paper provided by Stata Users Group in its series North American Stata Users' Group Meetings 2003 with number 07.

    as in new window
    Length:
    Date of creation: 08 Jan 2003
    Date of revision:
    Handle: RePEc:boc:asug03:07

    Contact details of provider:
    Web page: http://www.stata.com/meeting/2nasug
    More information through EDIRC

    Related research

    Keywords:

    This paper has been announced in the following NEP Reports:

    References

    No references listed on IDEAS
    You can help add them by filling out this form.

    Citations

    Lists

    This item is not listed on Wikipedia, on a reading list or among the top items on IDEAS.

    Statistics

    Access and download statistics

    Corrections

    When requesting a correction, please mention this item's handle: RePEc:boc:asug03:07. See general information about how to correct material in RePEc.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Christopher F Baum).

    If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

    If references are entirely missing, you can add them using this form.

    If the full references list an item that is present in RePEc, but the system did not link to it, you can help with this form.

    If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your profile, as there may be some citations waiting for confirmation.

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.