2001 American Community Survey Minimum and Maximum Codes
The following eleven housing variables and nine person variables are top-coded in the 2001 American Community Survey Public Use Microdata Sample:
|Housing Variables||IPUMS Variables||Person Variables||IPUMS Variables|
|Electricity (monthly cost) - ELEP||COSTELEC||Wages or salary income last year - WAGP||INCWAGE|
|Gas (monthly cost) - GASP||COSTGAS||Self-employment income last year (signed) - SEMP||INCBUS00|
|Water (yearly cost) - WATP||COSTWATR||Interest, dividends, and net rental income last year (signed) - INTP||INCINVST|
|House Heating fuel (yearly cost) - FULP||COSTFUEL||Social security income last year - SSP||INCSS|
|Condo fee (monthly amount) - CONP||CONDOFEE||Supplementary Security Income last year - SSIP||INCSUPP|
|Monthly rent - RNTP||RENT||Public assistance income last year - PAP||INCWELFR|
|Property taxes (yearly amount) - TAXP||PROPTX99||Retirement income last year - RETP||INCRETIR|
|Fire/hazard/flood insurance (yearly amount) - INSP||PROPINSR||All other income last year - OIP||INCOTHER|
|Mortgage payment (monthly amount) - MRGP||MORTAMT1||Age - AGEP||AGE|
|Second mortgage payment (monthly amount) - SMP||MORTAMT2|
|Mobile home costs (yearly amount) - MHP||MOBLHOME|
The Census Bureau derived its top-codes based on the following rules:
- Within each state, all base dollar amounts are top-coded using the mean of all cases greater than the topcode national minimum value.
- The maximum bottom-coding value for all component income dollar amounts which can be negative is $10,000.
- Recodes of dollar amounts use the rounded top-coded or bottom-coded base dollar amounts without any additional top-coding or bottom-coding.
- Top-coded property taxes are further assigned to one of 68 categories.
- AGE is top-coded using the state mean of all cases greater than 90.
The top-codes listed below reflect the IPUMS data. Users should be aware that the IPUMS top-codes diverge from the top-codes listed 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. Similarly, the number of minutes one takes to get to work is documented as a three-digit variable, but is released only as a two-digit variable.
The top-codes and bottom-codes for the 2001 ACS file are available here (.xls).