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Statistics Notes: Interaction 2: compare effect sizes not P values
Open accessAbstract
As we have previously described,1 the statistical term interaction relates to the non-independence of the effects of two variables on the outcome of interest. For example, in a controlled trial comparing a new treatment with a standard treatment we may want to examine whether the observed benefit was the same for different subgroups of patients. A common approach to answering this question is to analyse the data separately in each subgroup. Here we illustrate this approach and explain why it is incorrect. One of several subgroup analyses in a trial of antenatal steroids for preventing neonatal respiratory distress syndrome2 was performed to see whether the effect of treatment was different in mothers who did or did not develop pre-eclampsia. Among mothers with preeclampsia 21.2% (7/33) of babies whose mothers were given dexamethasone developed neonatal respiratory …
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Research works printed but not linked: 3
- Altman, 1996, Interaction 1: heterogeneity of effects., BMJ, 313, 486, 10.1136/bmj.313.7055.486 · DOI
- 1981, Effect of antenatal dexamethasone administration on the prevention of respiratory distress syndrome., Am J Obstet Gynecol, 141, 276, 10.1016/S0002-9378(16)32633-3 · DOI · Paper page
- Cockburn, 1980, Maternal vitamin D intake and mineral metabolism in mothers and their newborn infants., BMJ, 281, 11, 10.1136/bmj.281.6232.11 · DOI · Paper page
Cited by
Moher, D., Hopewell, S., Schulz, K. F., Montori, V., Gotzsche, P. C., Devereaux, P. J., Elbourne, D., Egger, M., & Altman, D. G. (2010) · BMJ · doi:10.1136/bmj.c869 · Cited by 8,883
Self-citationThe Revised CONSORT Statement for Reporting Randomized Trials: Explanation and Elaboration
Altman, D. G., Schulz, K. F., Moher, D., Egger, M., Davidoff, F., Elbourne, D., Gøtzsche, P. C., Lang, T., & for the CONSORT Group (2001) · Annals of Internal Medicine · doi:10.7326/0003-4819-134-8-200104170-00012 · Cited by 3,835
Self-citationInteraction revisited: the difference between two estimates.
Altman, D. G., & Bland, J. M. (2003) · BMJ · doi:10.1136/bmj.326.7382.219 · Cited by 3,203
Self-citationStatistical tests, P values, confidence intervals, and power: a guide to misinterpretations
Greenland, S., Senn, S. J., Rothman, K. J., Carlin, J. B., Poole, C., Goodman, S. N., & Altman, D. G. (2016) · European Journal of Epidemiology · doi:10.1007/s10654-016-0149-3 · Cited by 3,200
Self-citationMoher, D., Hopewell, S., Schulz, K. F., Montori, V., Gøtzsche, P. C., Devereaux, P. J., Elbourne, D., Egger, M., & Altman, D. G. (2012) · International Journal of Surgery · doi:10.1016/j.ijsu.2011.10.001 · Cited by 2,345
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Metadata
- Authors
- Matthews, J. N. S., & Altman, D. G.
- Venue
- BMJ
- Publisher
- BMJ
- Published
- 1996-09-28
- Volume
- 313
- Issue
- 7060
- Pages
- 808
- ISSN
- 0007-1447 (ISSN-L)
- 0959-8138
- 1468-5833
- OpenAlex
- W2025837572
- Cited by
- 174
- References
- 0
- FWCI
- 1.98
- Type
- journal article
- Language
- en
- Open access
- bronze
- Licence
- www.bmj.com/company/legal-information/terms-conditions/legal-information/tdm-licencepolicy (tdm)
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Contains information from the Semantic Scholar Academic Graph Datasets, made available under the ODC Attribution License (ODC-BY 1.0).
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