Many other statisticians disagree with that stand. T o illustrate the difficulties of obtaining accurate population figures, Wright uses an analogy. Suppose 10 enumerators, working independently, are asked to determine the number of people at a basketball game during halftime. The ticket sales count won't do because some people might have sneaked in or legitimately gained admission without tickets, while others who bought tickets may not have shown up. Counting people in the stands during halftime presents other problems.
Spectators come and go, some exiting the arena and others seeking refreshments or switching seats.
As a result, some people may be counted twice and others missed completely. Almost certainly, the 10 enumerators would come up with 10 different counts. That variability represents what statisticians call measurement error. Just like the estimates of attendance at a basketball game, censuses of the United States also contain measurement error, Wright says. Moreover, given limited resources, it's difficult to keep that measurement error small when counting a large and highly mobile population.