Jill Lacey and Junting Wang Describe what it takes to design an Election Day exit poll Chris Olsen reviews the book Applied Spatial Statistics for Public Health Data THE MAGAZINE FOR STUDENts OF STATIstICS : : ISSUE 50 CASE STUDY: The FiveThirtyEight.com Predictive Model of the 2008 Presidential Election Looking for a JOB? http://jobs.amstat.org Your career as a statistician is important to the ASA and we are here to help you realize your professional goals. The ASA JobWeb is a targeted job database and résumé-posting service that will help you take advantage of valuable resources and opportunities. Check out the many services available from the ASA JobWeb. VIEW ALL JOBS ➜ Search by keyword, job category, type of job, job level, state/country location, job posting date, and date range of job posting. ADvaNCED SEARCH ➜ Use multiple search criteria for more targeted results. MAINTAIN A PERSONAL ACCOUNT ➜ Manage your job search, update your profile, and edit your résumé. 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CASE STUDY: The FiveThirtyEight.com Predictive Model of 3 Designing and Implementing an the 2008 Presidential Election Day Exit Poll Election JILL N. Lac EY is a senior survey Designing and specialist at the U.S. Government Accountability Office and performed Implementing an work on this article while a graduate Election Day Exit Poll page 3 student at The George Washington 10 University. When Randomization Meets Reality An JUNTING WA NG is an engineer impact evaluation in the at China Communications and Republic of Georgia 16 Transportation Association in China. When Randomization Meets Reality An impact evaluation in columns the Republic of Georgia COLUMNS MIR A ND A BERISHVILI is an associate professor at Georgian EDITOR'S COLUMN 2 Technical University in Tbilisi. RU SIMULATING Matching Items and CELESTE TA RRI C ONE is an assis- Collecting Coupons 21 tant director for the Millennium Challenge Corporation, where she is a monitoring and evaluation STATISTICAL -SINGS specialist for country programs in Black Death Georgia, Honduras, and Vanuatu. A review of Applied Spatial Statistics for Public Health Data 26 Safaa AMER is employed by NORC at the University of Chicago ReFERENCES and and does poverty program impact Additional evaluation in Georgia for the Reading List 28 Millennium Challenge Corporation page 10 and its Georgian counterpart, MCG. EDITOR’S COLUMN DIRECTOR OF EDUCATION Martha Aliaga American Statistical Association 732 North Washington Street, Alexandria, VA 22314-1943 [email protected] The guest editors for this issue of STATS are Jill Lacey and Fritz Scheuren. Lacey is a graduate of the certificate program in survey design and data analysis at The George Washington University EDITORIAL BOARD (GWU). Scheuren, a past-president of the American Statistical Peter Flanagan-Hyde Mathematics Department Association, was her instructor, aided by Ali Mushtaq. Phoenix Country Day School, Paradise Valley, AZ 85253 [email protected] Schuyler W. Huck Department of Educational Psychology and Counseling University of Tennessee Knoxville, TN 37996 ome background about this change in [email protected]@cr.k12.ia.us editorship might be in order before we talk Sabout the contents of the current issue. As Jackie Miller many of you will remember, Paul Fields was the Department of Statistics STATS editor from 2005 to 2008. He had to step The Ohio State University, Columbus, OH 43210 [email protected] down to work on other projects. We volunteered to fill in as co-editors for the time being, and we Chris Olsen are not sorry! So far, we have found the experience Department of Mathematics stimulating and humbling—but we are not Thomas Jefferson High School, Cedar Rapids, IA 53403 [email protected] stumbling, thanks to the great staff at the ASA office, led by Megan Murphy and Martha Aliaga. Bruce Trumbo As “newbies,” we quickly learned that getting Department of Statistics together a good set of articles is the first step to California State University, East Bay, Hayward, CA 94542 [email protected] putting out an issue. Here, we were fortunate. Fields left us an inventory of fine articles from which to draw. Regular columns by Chris Olsen and Bruce Trumbo will be found in this issue, PRODUCTION/DESIGN along with a topical article by Miranda Berishvili, Megan Murphy Communications Manager Celeste Tarricone, and Safaa Amer about the use American Statistical Association of randomization in agricultural experimentation. Val Snider Because the experiments in the latter took place in Publications Coordinator American Statistical Association the country of Georgia, we have provided context Melissa Muko by reprinting an article from Amstat News that Graphic Designer/Production Coordinator appeared last October. American Statistical Association As we all know, the United States went through STATS: The Magazine for Students of Statistics a major presidential election in 2008, so we (ISSN 1053-8607) is published three times a year, by the American Statistical Association, devoted the cover story to that process. Indeed, 732 North Washington Street, Alexandria, we lead with “Case Study: The FiveThirtyEight. VA 22314-1943 USA; (703) 684-1221; www. com Predictive Model of the 2008 Presidential amstat.org. STATS is published for beginning statisticians, including high school, undergrad- Election.” Author Adam Felder took the fall 2008 uate, and graduate students who have a special GWU certificate course on survey management. As interest in statistics, and is provided to all stu- part of the class, students conducted exit polls in dent members of the ASA at no additional cost. Subscription rates for others: $15.00 a year for the Washington, DC, area. The paper “Designing ASA members; $20.00 a year for nonmembers; and Implementing an Election Day Exit Poll,” by $25.00 for a Library subscription. Jill Lacey and Junting Wang, is an outgrowth of Ideas for feature articles and materials for departments should be sent to Editor Paul J. that course, as well. Fields at the address listed above. Material Trumbo and Luther B. Scott wrote “Matching must be sent as a Microsoft Word document. Items and Collecting Coupons” for the R U Accompanying artwork will be accepted in four graphics formats only: EPS, TIFF, PDF, Simulating column. As statisticians, our love and or JPG (minimum 300 dpi). No articles in appetite for real data in increasingly close to our WordPerfect will be accepted. love for simulated data. Trumbo and Scott tap into Requests for membership information, ad- this growing strength. vertising rates and deadlines, subscriptions, and general correspondence should be ad- The last article, the Statistical -sings column, is a dressed to the ASA office. light-hearted piece from Olsen that captures the tone Copyright (c) 2009 American Statistical Association. we wanted for this issue—interesting and instructive. This, too, comes from Fields. Thanks again! 2 ISSUE 50 :: STATS ISSUE 50 :: STATS 3 CASE STUDY: The FiveThirtyEight.com Predictive Model of the 2008 Presidential Election by Adam Felder here has already been a great deal of effect. Large numbers of independent pollsters analysis on the 2008 United States were able to disseminate national- and state-level Telection in which Barack Obama was polling results to the public. It is not a stretch to elected president. Much of this analysis is devoted say that on any given business day from the time of to Obama’s “ground game,” a grassroots network the first presidential debate onward, at least a dozen of volunteers who helped register voters in record- polls from various organizations were released. breaking numbers and, perhaps more importantly, To combat this saturation of information, poll got those voters to actually vote on or before aggregation sites exist. These sites compile all November 4. Much of this ground game was polling for a given area (e.g., a state or national poll) founded in the so-called “netroots,” a term used to and combine it in an attempt to give a clearer picture describe Internet-based grassroots activism. of the state of the race. However, there exist different The Obama campaign was not alone in its use of methodologies for aggregation. Some lump all polls the Internet; political analysts also used it to great together and treat them equally. Others weight by timeliness of a poll; a poll taken a week before Election Day is given greater weight than a poll taken a month before Election Day. Still others, such as FiveThirtyEight.com, allow polls from demographically similar states to influence one another’s results in the absence of new information. In short, various aggregation sites employ mixed methodologies to make predictions. ISSUE 50 :: STATS 3 Methodology About FiveThirtyEight.com FiveThirtyEight.com has several unique features FiveThirtyEight.com, named for the number of electoral votes to its model that differentiate it from similar awarded in a presidential election, is owned and operated by sites. The first major difference is in how polls Nate Silver. The site launched in March 2008, and Silver (using the are weighted.