As the nation's leading statistical agency,
your Census Bureau continuously evaluates
and improves the methods by which we collect data.
As scientists, demographers and statisticians, we are obligated
to ensure that all the information we provide
to the nation is as accurate as possible.
Since we deal with numbers on such a large scale,
it is imperative we continuously check our work,
because a small error in a large population can create an even
larger error in a smaller, related population.
We recently came across this scenario
when analyzing the number
of same-sex couples in the United States.
Let's take a look at how a mere mismarking on a form can result
in an inaccurate count of a group within the population.
A simple math equation can illustrate this.
Let's say there are one thousand circles
and one hundred thousand squares, where each square
and circle is the equivalent to one thousand.
If just one percent of the squares are erroneously counted
as circles, that's one thousand squares now listed as circles.
This mislabeling of squares would inaccurately represent the
total number of circles by doubling their amount.
Through this example we can see the importance of accuracy.
In our work, we know that the design
of a form can affect how people answer the questions
and even introduce errors into the process.
A data capture error can happen when the human eye misreads
or skips wording on a survey questionnaire.
The Census Bureau takes this into account
as we process responses and design our surveys.
We learned from the 2007 American Community Survey
that when boxes were placed like this, respondents
or door-to-door census takers may accidentally mismark their
gender, because the eye is not registering all
that is on the page.
Additionally, a mere extension of a marked line may result
in an erroneous response.
A change in the placement of boxes can fix this.
We found that moving the boxes from here -- to here --
almost completely eliminated these kinds of errors
on the American Community Survey.
We do extensive testing
of how respondents' eyes track the information presented
on the form.
Upon further study of the 2010 Census results, we discovered
that a small percentage
of enumerators erroneously recorded the gender
of couples residing within some of the households surveyed.
While we discovered this issue on the ACS form in enough time
to make the necessary changes needed to the 2010 Census form
that was delivered to your home,
the forms that the enumerators used
when going door-to-door were unable to be corrected in time.
So, how does this type of data capture error affect the number
of same-sex couple results for the 2010 Census?
This graphic illustrates same-sex
and opposite-sex couples.
Let's say that a county has one thousand same-sex couples
and one hundred thousand opposite-sex couples.
If just one percent
of the opposite sex couples are erroneously reported
as same-sex couples, that's one thousand additional couples now
listed as same-sex.
This mismarking results in responses
that artificially inflate the number
of recorded same-sex couples.
Census Bureau staff developed another set of estimates
to provide a more accurate way
to measure same-sex couple households.
The revised numbers, in addition to the original
and the American Community Survey estimates,
are now available.
Providing the new set of estimates ensures
that all groups within our population have an accurate
representation so that we can better reflect
who we are, as a nation.
Your Census Bureau is constantly evaluating data collection
operations to better measure the nation's people,
places and economy.