Coverage error

[3] For example, a researcher may wish to study the opinions of registered voters (target population) by calling residences listed in a telephone directory (sampling frame).

Bias could also occur if some phone numbers listed in the directory do not belong to registered voters.

[5] For example, suppose a researcher is using Twitter to determine the opinion of U.S. voters on a recent action taken by the U.S. President.

[6] For example, a researcher might want to study the relationship between the letter grades received by third graders in a particular school district and the wages that these same children earn when they become adults.

In this case, the researcher is interested in all third graders in the district who grow-up to be adults (target population).

[8] One way to reduce coverage error is to rely on multiple sources to either build a sample frame or to solicit information.

This approach had the added benefit of cost reduction as the majority of people responded by mail and did not require a field visit.

Coverage errors in the U.S. Census have the potential impact of allowing people groups to be underrepresented by the government.

Although the efforts of the CFU and FV improved the 2010 Census accuracy, more study was recommended to address the question of differential undercounts.