Humans and models: converging ‘truths’

INTERNATIONAL JOURNAL OF EPIDEMIOLOGY rejected. To inspire his followers, Morris had attached his two exceedingly long and aggressive reviews of our paper (12 858 words and 5291 words, respect- ively), calling for critical letters in abundance to the IJE editors. Breaking unwritten confidentiality and courtesy rules of the peer-review process, Morris dis- tributed his slandering criticism of our study to people working for the same cause. Rather than resorting to such selective distribution among friends, Morris should make both reviews freely available on the internet by posting them in their entirety on his pro circumcision homepage (www.circinfo.net). Alternatively, interested readers should feel free to request them from me at the e-mail address above. Despite poorly founded criticisms and attempts at obstruction our findings suggest that male circumci- sion may be associated with hitherto unappreciated negative sexual consequences in a non-trivial propor- tion of men and women. Further carefully conducted studies are needed. References Morris BJ. Why circumcision is a biomedical imperative for the 21st century. Bioessays 2007;29:1147–58. Perneger TV. What’s wrong with Bonferroni adjustments. Br Med J 1998;316:1236–38. Barros AJ, Hirakata VN. Alternatives for logistic regres- sion in cross-sectional studies: an empirical comparison of models that directly estimate the prevalence ratio. BMC Med Res Methodol 2003;3:21. Krieger JN, Mehta SD, Bailey RC et al. Adult male cir- cumcision: effects on sexual function and sexual satisfac- tion in Kisumu, Kenya. J Sex Med 2008;5:2610–22. Kigozi G, Watya S, Polis CB et al. The effect of male cir- cumcision on sexual satisfaction and function, results from a randomized trial of male circumcision for human immunodeficiency virus prevention, Rakai, Uganda. BJU Int 2008;101:65–70. Circleaks.http://circleaks.org/index.php?title¼Brian_Morr is (8 August 2011, date last accessed). Circleaks.http://circleaks.org/index.php?title¼Jake_H._ Waskett (8 August 2011, date last accessed). Morris BJ. Renin, genes, and beyond: 40 years of molecu- lar discoveries in the hypertension field. Hypertension YouTube.http://www.youtube.com/v/7yDvL4hNny4 August 2011, date last accessed). Morris BJ, Wodak A. Circumcision survey misleading. Aust N Z J Public Health 2010;34:636–37. Waskett JH, Morris BJ, Weiss HA. Errors in meta-analysis by Van Howe. Int J STD AIDS 2009;20:216–18. Waskett JH, Morris BJ. Fine-touch pressure thresholds in the adult penis. BJU Int 2007;99:1551–52. doi:10.1093/ije/dyr181 Advance Access publication 28 November 2011 s The Author 2011; all rights reserved. Humans and models: converging ‘truths’ From TIM A BRUCKNER 1 * and CLAIRE MARGERISON-ZILKO 2 Program in Public Health & Department of Planning, Policy, and Design, University of California, Irvine, CA, USA and Population Research Center & Center for Social Work Research, University of Texas, Austin, TX, USA *Corresponding author. Program in Public Health & Department of Planning, Policy, and Design, University of California, 202 Social Ecology I, Irvine, CA, 92697, USA. E-mail: tim.bruckner@uci.edu We thank Jay Kaufman for his thoughtful commen- tary 1 regarding our recent manuscript in which we reported a positive relation between acute income gains and accidental deaths among Cherokee Indians in rural North Carolina. 2 Although we agree with many of Kaufman’s points, we would like to respond to a key question that holds relevance to most analyses using time series data: how should epi- demiologists approximate the counterfactual value of a population exposed at a specific point in time? One approach to deriving counterfactual values in time involves using a model-based framework. In our analysis of the Cherokee response to acute and large cash disbursements from a local Casino, we em- ployed a Poisson regression with a conventional log-linear functional form. 3 To control for confound- ing by temporal patterns in accidental deaths (e.g. seasonality), we included indicator variables for cal- endar months and years. Identification of an effect of the Casino payments on accidental deaths, therefore, relies on a systematic deviation—in the 20 exposed months of the Casino disbursements—above expected values derived from the specific underlying (multi- plicative) functional form of accidental deaths. The analyst, of course, could impose different model- based assumptions regarding temporality of accidental deaths (e.g. additivity), yet Kaufman notes the prob- lem of insufficient statistical power to test such as- sumptions. In other words, the analyst has limited ability to detect what we call ‘wrong model bias’ in the functional form of a time series. An alternative approximation of the counterfactual value, which Kaufman suggests, involves using a comparison series of accidental deaths among