Plyer used her closing minutes to discuss some work that GNOCDC is doing to work with one major challenge associated with ACS data, which is the presentation of the uncertainty inherent in the estimates. As Terpstra and IMPACT do for neighborhoods in Chicago and places within neighborhoods, GNOCDC is planning on rolling out additional ACS data tables by neighborhood for New Orleans. Plyer displayed a couple of screenshots of the tabular interface, including columns for the standard error of each estimate. She said that other NNIP partners had just posted the standard errors there, without much more context than that. GNOCDC is currently completing work on a small online widget as a companion piece for the new ACS tables; for instance, users can enter the percentages and the associated standard errors and have displayed a plain-English, yes/no statement as to whether there is a statistically significant difference or not. Users will be able to access a similar widget after they use other features of the site, such as combining income categories. Through these easy-to-use features, they hope to make the margins of error less mysterious (or frightening) to their downstream data users.13
Closing the session, Russ Paulsen (executive director for community preparedness and resilience, American Red Cross) conceded that his remarks would be unlike other presentations in that they would not be ACS-centric; he said that he would be unable to sort out exactly what information Red Cross derives from the ACS versus the CPS versus any other data source, and that analysts at the American Red Cross national headquarters tend to use data products prepared by outside vendors. What the workshop steering committee asked him to do was to talk through a general framework through which data like those from the ACS are used in disaster response, recovery, and preparedness planning—the field in which Paulsen said he has some 20 years of experience, including the major response to Hurricane Katrina discussed by Plyer.
simply “don’t have spreadsheets” and lack the ability to directly manipulate data. This thread would be revisited in the media perspectives session; see Chapter 4.
13The ACS margins of error at the census tract level, and some oddities in the data, are “the bane of our existence with ACS data,” Plyer said—ending her talk by showing a map of tract-level median household income derived from 2006–2010 ACS data. Much of the picture that results makes sense; relatively wealthy and relatively poor areas of the city stand out from each other—except for a one-tract pocket of the otherwise low-income Lower Ninth Ward that shows a “higher than average” median income. As is well known, the Lower Ninth Ward suffered Katrina’s worst devastation, and still struggles to recover. Put bluntly by Plyer, “we don’t know what to do with this”—the anomalous item has baffled GNOCDC, local housing planners, and other officials.