DOBSON — Even Surry County residents who returned their census forms on time this year could be getting a visit from a census worker this summer, officials say.

Census questionnaires that someone mailed early, but contain mistakes, will prompt a knock on the door by a program representative. For example, if the number of people listed at an address doesn’t match the number of names provided on the form, clarification will be needed.

This coverage follow-up effort will run until mid-August, U.S. Census Bureau officials said last week.

Some heads of households who mailed in forms already have received a visit from a census worker for reasons including incomplete or conflicting answers or questionnaires received after a mail-in deadline. The mail-participation rate for North Carolina was 74 percent.

Presently, the every-10-year head count is in the non-response follow-up phase in which workers are going door-to-door to collect data for residents who did not mail in census forms at all by the deadline. This part of the process is scheduled to end on July 10.

Also during July, another quality-control measure will involve census personnel double-checking vacant households and those deleted as nonexistent on April 1, the reference date for the 2010 Census. They also will visit housing units from which the bureau received blank or incomplete forms.

During August, workers are scheduled to visit households for which forms have been received but whose addresses do not match those in the bureau’s master file. This operation also seeks to resolve suspected duplicate addresses within the same block.

“These operations are supplemented by other quality-assurance processes to maximize accuracy,” William W. Hatcher, Charlotte regional director for the Census Bureau, said of this summer’s activities.

“In some cases, that means a home may be visited more than once,” Hatcher added. “If you are one of the small percentage of North Carolina homes that are visited, please take a few minutes to speak with the census taker. Our mission is to count everyone, once and in the right place. We check and double-check to make sure we get it right.”

Census takers will have an official identification badge and many also carry a black bag marked with the words “U.S. Census Bureau.” They will never ask to come into a home or seek bank, credit card or Social Security numbers, officials say.