Top Coded and Bottom Coded Values by State
The table below shows the top-code and bottom-code values by state. These top-codes and bottom-codes were derived based on the following rules:
- Age, travel time to work, and all base dollar amounts are top-coded using the state mean of all cases greater than or equal to the top-code state minimum value. The only exception to the top-code state minimum value is TAX which uses the top-code national minimum value. Income amounts which can have negative values (SEMP and INTP) are bottom-coded using the state mean of all cases less than or equal to the bottom-code state maximum value. Recodes of dollar amounts use the rounded top-coded/bottom-coded base dollar amounts without any additional top-coding/bottom-coding.
- Top-coded property taxes are further assigned to one of 68 categories.
Users should be aware that the IPUMS top- and bottom-codes diverge from those in the Census Bureau's documentation for two main reasons:
- The Census Bureau rounds its top-coded values before releasing the public-use data. For example, wage and salary income is rounded to the nearest $1,000 such that an actual top-coded value of $158,333 would become $158,000 in the public-use data. In most cases, these top-codes are off by no more than 0.1% from what would have been obtained if the Census Bureau had released the original, non-rounded top-codes. Monthly electricity and gas costs variables are rounded to the nearest $10. Because IPUMS multiplies these amounts by 12 to obtain the annual electricity and gas costs, this rounding error is similarly multiplied by 12. Still, most IPUMS utility top-codes diverge from the non-rounded utility top-codes by no more than 1%.
- While the Census Bureau documents top-codes for property taxes as actual dollar amounts, the public-use version of this variable is collapsed into sixty-nine categories.