All American Community Survey (ACS) estimates are currently released with their associated margin of error (MOE). However, many users do not think that the MOE provides enough information about an estimate’s reliability. We conducted usability testing to examine whether the addition of reliability indicators to new prototypes of ACS data tables helped people use the tables with greater accuracy, efficiency, and satisfaction. All three prototypical reliability indicators were based on the coefficient of variation (CV), which is defined as the standard error divided by the mean of the estimate.
Each prototypical table with a reliability indicator tested in this study implemented a color-coded “Reliability” column and a legend explaining the meaning of the color codes to provide users with guidance as to whether the proportion of error to the estimate itself might be considered unacceptably high.
Each prototype table was defined by the number of “levels” that its Data Reliability Indicator used to label the estimates. Specifically, the two-level indicator had the levels “blank” (CV<=0.30) and “use caution” (yellow; CV>0.30); the three-level indicator included the levels “good” (green; CV<=0.30), “fair” (yellow; 0.30<CV<=0.61), and “poor” (red; CV>0.61); and the four-level indicator had the levels “excellent” (green; CV<=0.10), “good” (yellow; 0.10<CV<=0.30), “fair” (orange; 0.30<CV<=0.61), and “poor” (red; CV>0.61). Nine participants completed usability tasks using the prototypes, and three participants completed the tasks using baseline versions of the current ACS data tables without the indicators. Full versions of the prototype tables can be found in Appendix A.
The results showed that the four-level indicator was associated with the highest accuracy and satisfaction scores. In fact, eight of the twelve participants indicated that they preferred the four-level indicator overall. Users were able to complete the tasks more efficiently using the prototypes than the baseline tables, and they also expressed a strong preference for all of the prototypes over the baseline tables.
Source: U.S. Census Bureau, Statistical
Published online: February 18, 2009
Last revised: February 12, 2009
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