(a) The governmental unit shall provide whatever evidence it has relevant to the request at the time of filing. The Census Bureau may request further evidence when necessary. The evidence submitted must be consistent with the criteria, standards, and regular processes the Census Bureau employs to generate the population estimate. The Census Bureau has revised the challenge process to no longer accept estimates developed from methods different from those used by the Census Bureau. In the revised challenge process, the Census Bureau will only accept a challenge when the evidence provided identifies the use of incorrect data, processes, or calculations in the estimates.

(b) For counties and statistical equivalents, the Census Bureau uses a cohort-component of change method to produce population estimates. Each year, the components of change are updated. These components include births, deaths, migration, and change in the group quarters population. The Census Bureau will consider a challenge based on additional information on one or more of the components of change or about the group quarters population in a locality.

(c) For minor civil divisions and incorporated places, the Census Bureau uses a housing unit method to distribute the county population. The components in this method include housing units, occupancy rates, and persons per household plus an estimate of the population in group quarters. The Census Bureau will consider a challenge based on data related to changes in an area's housing stock, such as data on demolitions, condemned units, uninhabitable units, building permits, or mobile home placements or other comparable housing inventory based data. The Census Bureau will also consider a challenge based on additional information about the group quarters population in a locality.

(d) The Census Bureau will also provide a guide on its Web site as a reference for governmental units to use in developing their data as evidence to support a challenge to the population estimate. In addition, a governmental unit may address any additional questions by contacting the Census Bureau at the address provided in §90.7.