Applied Spatial Analysis and Policy

, Volume 12, Issue 4, pp 941–963 | Cite as

Hidden in Plain Sight: A Machine Learning Approach for Detecting Prostitution Activity in Phoenix, Arizona

  • Edward HelderopEmail author
  • Jessica Huff
  • Fred Morstatter
  • Anthony Grubesic
  • Danielle Wallace


Prostitution has been a topic of study for decades, yet many questions remain about where prostitution occurs. Difficulty in identifying prostitution activity is often attributed to the hidden and seemingly victimless nature of the crime. Despite numerous challenges associated with policing street prostitution, these encounters become more difficult to identify when they take place indoors, especially in locations away from public view, such as hotels. The purpose of this paper is to develop a strategy for identifying hotel facilities and surrounding areas that may be experiencing elevated levels of prostitution activity using high-volume, user-generated data, namely hotel reviews written by guests and posted to A unique synthesis of methods including data mining, natural language processing, machine learning, and basic spatial analysis are combined to identify facilities that may require additional law enforcement resources and/or social/health service outreach. Prostitution hotspots are identified within the city of Phoenix, Arizona and policy implications are discussed.


Natural language processing Machine learning Prostitution Spatial analysis Phoenix 


Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.


  1. Anstine, J. (2003). Property values in a low populated area when dual noxious facilities are present. Growth and Change, 34 (3), 345–358.Google Scholar
  2. Barnard, M. A. (1993). Violence and vulnerability: conditions of work for streetworking prostitutes. Sociology of Health & Illness, 15(5), 683–705. Scholar
  3. Benson, C., & Matthews, R. (2000). Police and prostitution: Vice squads in Britain. In R. Weitzer (Ed.), Sex for sale: Prostitution, pornography, and the sex industry (pp. 245–264). New York: Routledge.Google Scholar
  4. Boels, D., & Verhage, A. (2016). Prostitution in the neighbourhood: impact on residents and implications for municipal regulation. International Journal of Law, Crime and Justice, 46, 43–56.Google Scholar
  5. Bogomolov, A., Lepri, B., Staiano, J., Oliver, N., Pianesi, F., & Pentland, A. (2014). Once upon a crime: Towards crime prediction from demographics and mobile data. In Proceedings of the 16th international conference on multimodal interaction (pp. 427–434). New York: ACM. Scholar
  6. Bojanowski, P., Grave, E., Joulin, A., & Mikolov, T. (2016). Enriching Word Vectors with Subword Information. ArXiv:1607.04606 [Cs]. Retrieved from Retrieved October 17, 2018.
  7. Breiman, L. (2001). Random forests. Machine Learning, 45(1), 5–32.Google Scholar
  8. Butcher, K. (2003). Confusion between prostitution and sex trafficking. The Lancet 361, (9373), 1983.Google Scholar
  9. Census Bureau. (2017). State population totals and components of change: 2010–2017. Retrieved from: Retrieved October 17, 2018.
  10. Chokshi, N. (2015). The religious states of America, in 22 maps. Washington Post. URL:
  11. Chudakov, B., Ilan, K., Belmaker, R. H., & Cwikel, J. (2002). The motivation and mental health of sex workers. Journal of Sex & Marital Therapy, 28(4), 305–315.Google Scholar
  12. Church, S., Henderson, M., Barnard, M., & Hart, G. (2001). Violence by clients towards female prostitutes in different work settings: questionnaire survey. BMJ (Clinical Research Ed.), 322(7285), 524–525. Scholar
  13. Cunningham, S., & Kendall, T. D. (2011). Prostitution 2.0: The changing face of sex work. Journal of Urban Economics, 69(3), 273–287. Scholar
  14. Cunningham, S., & Shah, M. (2014). Decriminalizing indoor prostitution: Implications for sexual violence and public health (working paper no. 20281). National Bureau of Economic Research.
  15. Dank, M.L., Khan, B., Downey, P.M., Kotonias, C., Mayer, D., Owens, C., ... & Yu, L. (2014). Estimating the size and structure of the underground commercial sex economy in eight major US cities (p. 348). Washington, DC: Urban Institute.Google Scholar
  16. Day, S. E., & Ward, H. (2007). British policy makes sex workers vulnerable. BMJ (Clinical Research Ed.), 334, 185–187. Scholar
  17. Domingos, P. (2012). A few useful things to know about machine learning. Communications of the ACM, 55(10), 78–87.Google Scholar
  18. Farber, S. (1998). Undesirable facilities and property values: a summary of empirical studies. Ecological Economics, 24(1), 1–14.Google Scholar
  19. Farley, M. (2007). Prostitution and trafficking in Nevada: Making the connections. San Francisco: Prostitution Research & Education.Google Scholar
  20. Farley, M., & Barkan, H. (1998). Prostitution, violence, and posttraumatic stress disorder. Women & Health, 27(3), 37–49.Google Scholar
  21. Farley, M., & Kelly, V. (2000). Prostitution: a critical review of the medical and social sciences literature. Women & Criminal Justice, 11(4), 29–64.Google Scholar
  22. Gerber, M. S. (2014). Predicting crime using Twitter and kernel density estimation. Decision Support Systems, 61, 115–125. Scholar
  23. Gil, V. E., Wang, M. S., Anderson, A. F., Lin, G. M., & Wu, Z. O. (1996). Prostitutes, prostitution and STD/HIV transmission in mainland China. Social Science & Medicine, 42(1), 141–152.Google Scholar
  24. Gossop, M., Powis, B., Griffiths, P., & Strang, J. (1995). Female prostitutes in South London: use of heroin, cocaine and alcohol, and their relationship to health risk behaviours. AIDS Care, 7(3), 253–260.Google Scholar
  25. Gozdziak, E. M., & Collett, E. A. (2005). Research on human trafficking in North America: a review of literature. International Migration, 43(1–2), 99–128.Google Scholar
  26. Grubesic, T. H. (2006). On the application of fuzzy clustering for crime hot spot detection. Journal of Quantitative Criminology, 22(1), 77–105.Google Scholar
  27. Grubesic, T. H., & Murray, A. T. (2008). Sex offender residency and spatial equity. Applied Spatial Analysis and Policy, 1(3), 175–192.Google Scholar
  28. Harcourt, C., O'connor, J., Egger, S., Fairley, C. K., Wand, H., Chen, M. Y., ... & Donovan, B. (2010). The decriminalisation of prostitution is associated with better coverage of health promotion programs for sex workers. Australian and New Zealand Journal of Public Health, 34(5), 482–486.Google Scholar
  29. Havocscope. (2015). Prostitution: Prices and statistics of the global sex trade. Havocscope Books. Digital. 1st ed. Retrieved from: Retrieved October 17, 2018.
  30. Heiges, M. (2009). From the inside out: reforming state and local prostitution enforcement to combat sex trafficking in the United States and abroad. Minnesota Law Review, 94, 428.Google Scholar
  31. Hubbard, P. (1997). Red-light districts and toleration zones: geographies of female street prostitution in England and Wales. The Royal Geographical Society, 29(2), 129–140. Scholar
  32. Hubbard, P. (1998). Community action and the displacement of street prostitution: evidence from British cities. Geoforum, 29(3), 269–286.Google Scholar
  33. Hubbard, P., Boydell, S., Crofts, P., Prior, J., & Searle, G. (2013). Noxious neighbours? Interrogating the impacts of sex premises in residential areas. Environment and Planning A, 45(1), 126–141.Google Scholar
  34. Huff, J., Wallace, D., Riggs, C., Katz, C. & Choate, D. (2018). Examining the association between massage parlors and neighborhood crime. Crime & Delinquency. Online first: Scholar
  35. Jeal, N., & Salisbury, C. (2007). Health needs and service use of parlour-based prostitutes compared with street-based prostitutes: a cross-sectional survey. BJOG: An International Journal of Obstetrics & Gynaecology, 114(7), 875–881.Google Scholar
  36. Kaufman, L., & Rousseeuw, P. J. (2009). Finding groups in data: An introduction to cluster analysis (Vol. 344). Hoboken: Wiley.Google Scholar
  37. Kempadoo, K., Sanghera, J., & Pattanaik, B. (2015). Trafficking and prostitution reconsidered: New perspectives on migration, sex work, and human rights. Abingdon: Routledge.Google Scholar
  38. Krüsi, A., Kerr, T., Taylor, C., Rhodes, T., & Shannon, K. (2016). “They won”t change it back in their heads that we’re trash’: the intersection of sex work-related stigma and evolving policing strategies. Sociology of Health & Illness, 38(7), 1–14. Scholar
  39. Levy, O., Goldberg, Y., & Dagan, I. (2015). Improving distributional similarity with lessons learned from word embeddings. Transactions of the Association for Computational Linguistics, 3(0), 211–225.Google Scholar
  40. Larsen, E. N. (1992). The politics of prostitution control: interest group politics in four Canadian cities. International Journal of Urban and Regional Research, 16, 169–189.Google Scholar
  41. Liu, Y., Kliman-Silver, C., & Mislove, A. (2014). The tweets they are a-Changin: evolution of Twitter users and behavior. ICWSM, 30, 5–314.Google Scholar
  42. Lowman, J. (2000). Violence and the outlaw status of (street) prostitution in Canada. Violence Against Women, 6, 987–1011.Google Scholar
  43. Mack, E. A., & Grubesic, T. H. (2009). Forecasting broadband provision. Information Economics and Policy, 21(4), 297–311.Google Scholar
  44. Malleson, N., & Andresen, M. A. (2015). Spatio-temporal crime hotspots and the ambient population. Crime Science, 4(1), 10. Scholar
  45. Mansfield, C., Van Houtven, G., & Huber, J. (2001). The efficiency of political mechanisms for siting nuisance facilities: are opponents more likely to participate than supporters? The Journal of Real Estate Finance and Economics, 22(2), 141–161.Google Scholar
  46. Matthews, R. (2005). Policing prostitution: ten years on. British Journal of Criminology, 45(6), 877–895. Scholar
  47. McCleary, R., & Weinstein, A. C. (2009). Do “off-site” adult businesses have secondary effects? Legal doctrine, social theory, and empirical evidence. Law & Policy, 31(2), 217–235.Google Scholar
  48. McCutcheon, J. C., Mustaine, E. E., & Tewksbury, R. (2016). Working the stroll: prostitutes, Pimps, and Johns. Deviant Behavior, 37(12), 1449–1458. Scholar
  49. Mikolov, T., Chen, K., Corrado, G., & Dean, J. (2013). Efficient estimation of word representations in vector space. ArXiv:1301.3781 [Cs]. Retrieved from Retrieved October 17, 2018.
  50. Milrod, C., & Monto, M. (2016). Condom use, sexual risk, and self-reported STI in a sample of older male clients of heterosexual prostitution in the United States. American Journal of Men's Health, 10(4), 296–305.Google Scholar
  51. Opaluch, J. J., Swallow, S. K., Weaver, T., Wessells, C. W., & Wichelns, D. (1993). Evaluating impacts from noxious facilities: including public preferences in current siting mechanisms. Journal of Environmental Economics and Management, 24(1), 41–59.Google Scholar
  52. Oxford [Oxford English Dictionary]. (2018). Prostitution. URL:
  53. Pedregosa, F., Varoquaux, G., Gramfort, A., Michel, V., Thirion, B., Grisel, O., … Duchesnay, É. (2011). Scikitlearn: machine learning in python. Journal of Machine Learning Research, 12, 2825–2830.Google Scholar
  54. Prior, J., & Croft, P. (2012). Effects of sex premises on neighbourhoods: residents, local planning and the geographies of a controversial land use. New Zealand Geographer, 68, 130–140. Scholar
  55. Procon. (2017). US federal and state prostitution laws and related punishments. URL:
  56. Raphael, J., & Shapiro, D. L. (2004). Violence in indoor and outdoor prostitution venues. Violence Against Women, 10(2), 126–139. Scholar
  57. Roe-Sepowitz, D. E., Hickle, K. E., Loubert, M. P., & Egan, T. (2011). Adult prostitution recidivism: risk factors and impact of a diversion program. Journal of Offender Rehabilitation, 50(5), 272–285. Scholar
  58. Sanders, T. (2004). The risks of street prostitution: punters, police and protesters. Urban Studies, 41(9), 1703–1717. Scholar
  59. Schauer, E. J., & Wheaton, E. M. (2006). Sex trafficking into the United States: a literature review. Criminal Justice Review, 31(2), 146–169.Google Scholar
  60. Schill, M. H., Ellen, I. G., Schwartz, A. E., & Voicu, I. (2002). Revitalizing inner-city neighborhoods: New York city’s ten-year plan. Housing Policy Debate, 13(3), 529–566. Scholar
  61. Shannon, K., Rusch, M., Shoveller, J., Alexson, D., Gibson, K., & Tyndall, M. W. (2008). Mapping violence and policing as an environmental-structural barrier to health service and syringe availability among substance-using women in street-level sex work. International Journal of Drug Policy, 19(2), 140–147. Scholar
  62. Shmueli, G. (2010). To explain or to predict? Statistical Science, 25(3), 289–310.Google Scholar
  63. Smith, C. J., & Hanham, R. Q. (1981). Any place but here! Mental health facilities as noxious neighbors. The Professional Geographer, 33(3), 326–334.Google Scholar
  64. Steenbeek, W., Völker, B., Flap, H., & Oort, F. v. (2012). Local businesses as attractors or preventers of neighborhood disorder. Journal of Research in Crime and Delinquency, 49(2), 213–248. Scholar
  65. Van den Hoek, J. A., van Haastrecht, H. J., Scheeringa-Troost, B., Goudsmit, J., & Coutinho, R. A. (1989). HIV infection and STD in drug addicted prostitutes in Amsterdam: potential for heterosexual HIV transmission. Genitourinary Medicine, 65(3), 146–150.Google Scholar
  66. Wallace, D. (n.d.). Prostitution at hotels in Phoenix, AZ: Final report prepared for the Sandra Day O’Connor Institute. Demanding Justice Arizona. Retrieved from: Retrieved October 17, 2018.
  67. Wang, X., Gerber, M. S., & Brown, D. E. (2012). Automatic crime prediction using events extracted from twitter posts. In Social computing, behavioral - cultural modeling and prediction (pp. 231–238). Berlin, Heidelberg: Springer. Scholar
  68. Weitzer, R. (1999). Prostitution control in America: rethinking public policy. Crime, Law and Social Change, 32(1), 83–102.Google Scholar
  69. Weitzer, R. (2000a). The politics of prostitution in America. In R. Weitzer (Ed.), Sex for sale: Prostitution, pornography, and the sex industry (pp. 159–180). New York: Routledge.Google Scholar
  70. Weitzer, R. (2000b). Why we need more research on sex work. In R. Weitzer (Ed.), Sex for sale: Prostitution, pornography, and the sex.Google Scholar
  71. Weitzer, R. (Ed.). (2009). Sex for sale: Prostitution, pornography, and the sex industry. Routledge.Google Scholar
  72. Weitzer, R. (2010). The movement to criminalize sex work in the United States. Journal of Law and Society, 37(1), 61–84.Google Scholar
  73. Willis, B. M., & Levy, B. S. (2002). Child prostitution: global health burden, research needs, and interventions. The Lancet, 359(9315), 1417–1422.Google Scholar
  74. Winstanley, E. L., Steinwachs, D. M., Ensminger, M. E., Latkin, C. A., Stitzer, M. L., & Olsen, Y. (2008). The association of self-reported neighborhood disorganization and social capital with adolescent alcohol and drug use, dependence, and access to treatment. Drug and Alcohol Dependence, 92(1), 173–182. Scholar
  75. Yates, G. L., MacKenzie, R. G., Pennbridge, J., & Swofford, A. (1991). A risk profile comparison of homeless youth involved in prostitution and homeless youth not involved. Journal of Adolescent Health, 12(7), 545–548.Google Scholar
  76. Young, A., Boyd, C., & Hubbell, A. (2000). Prostitution, drug use, and coping with psychological distress. Journal of Drug Issues, 30(4), 789–800. Google Scholar

Copyright information

© Springer Nature B.V. 2018

Authors and Affiliations

  1. 1.Center for Spatial Reasoning & Policy Analytics, College of Public Service & Community SolutionsArizona State UniversityPhoenixUSA
  2. 2.School of Criminology and Criminal JusticeArizona State UniversityPhoenixUSA
  3. 3.Information Sciences Institute, Viterbi School of EngineeringUniversity of Southern CaliforniaLos AngelesUSA

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