An unrepresentative sample is unrepresentative regardless of the reason: a rejoinder to Amendola and Wixted
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Our objective was to assess Amendola and Wixted’s (Journal of Experimental Criminology, 2015b, this issue) response to our critique of their conclusions regarding simultaneous and sequential lineups.
We calculated the expected distribution of adjudicated guilty and not guilty cases in the smaller sample of cases for simultaneous and sequential lineups if a stratified sample of the larger set of cases had been used.
The results demonstrate more clearly our point that the 52 cases used in the Amendola and Wixted analysis were distributed in a manner that was not representative of the larger sample. Specifically, the 52 cases used by Amendola and Wixted overrepresented the number of cases not prosecuted for the sequential and underrepresented the number of cases not prosecuted for the simultaneous.
The outcome measure was strength of corroborating evidence, which is strongly related to whether or not the case was adjudicated guilty. Hence, when comparing simultaneous and sequential lineups, the small subsample that was tested should have reflected the nearly equivalent rates of adjudicated guilty for simultaneous versus sequential. Given the demonstrated unrepresentativeness of the small sample, no conclusions should be reached from these data.
KeywordsEyewitness Lineups Sequential lineups Eyewitness field experiment
- Amendola, K., Valdovinos, M. D., Slipka, M. G., Hamilton, E., Sigler, M., & Kaufman, A. (2014). Photo Arrays in Eyewitness Identification Procedures: Follow-up on the Test of Sequential versus Simultaneous Procedures (Study One) and an Experimental Study of the Effect of Photo Arrays on Evaluations of Evidentiary Strength by Key Criminal Justice Decision Makers (Study Two). Unpublished manuscript. Washington D.C.: Police Foundation, Washington, DC. Available at http://www.policefoundation.org/sites/g/files/g798246/f/201403/FINAL%20EWID%20REPORT--Police%20Foundation%281%29-1_0.pdf.
- Amendola, K., & Wixted, J. T. (2015a). Comparing the diagnostic accuracy of suspect identifications made by actual eyewitnesses from simultaneous and sequential lineups in a randomized field trial. Journal of Experimental Criminology. doi:10.1007/s11292-014-9219-2.