Census Base Rent Calculation for
Columbia County, WA

The 2000 Census Base Rent for Columbia County, WA used by HUD is $503.

This rent is the 40th percentile recent mover rent for the county group defined below because the recent mover sample size for Columbia County, WA is too small.


FMR Area Geography

Columbia County, WA has an insufficient 2000 Census sample of recent movers to compute its own recent mover rent. The number of units in the standard quality sample is also too small to compute a standard quality rent for Columbia County, WA alone. HUD requires a sample of at least 200 recent movers, but Columbia County, WA has fewer than 200 units in the protected data sample. Therefore, Columbia County, WA is assigned the recent mover rent for the combination of counties listed below, even though some members of the group may have a sufficient sample size for their own FMR or may be parts of metropolitan areas. Other FMR areas that use the same county group recent mover data are indicated by "*". Other FMR areas that use the same county group standard quality sample data are indicated by "#".

Members of the county group: Asotin County, WA; Columbia County, WA*#; Garfield County, WA*#; Walla Walla County, WA; Whitman County, WA.


User Note

In computing 2000 Census Base Rents, HUD actually uses data on rent distributions that are prohibited from public release under Title XIII to protect the confidentiality of respondents. The distributions used in this demonstration are rounded versions of the actual, protected data.

The rounding scheme is as follows:

0, count = 0
1 to 7, count = 4
all other counts are rounded to the nearest 5 (e.g., 10, 15, 20, 25, etc.)

CALCULATIONS USING THE ROUNDED DATA MAY NOT PRODUCE THE SAME RESULT AS CALCULATIONS USING THE PROTECTED DATA. THE DIFFERENCE BETWEEN HUD'S ACTUAL RESULTS AND THOSE DEMONSTRATED HERE IS INVERSELY RELATED TO THE SIZE OF THE FMR AREA. THAT IS, THE LARGER THE AREA, THE CLOSER THE CALCULATION BASED ON THE ROUNDED DATA IS LIKELY TO BE TO THE CENSUS BASE RENT COMPUTED FROM THE PROTECTED DATA.


Recent Mover and Standard Quality Rents

HUD uses rents for recent movers in standard quality units to set the 2000 Census Base Rent. "Standard Quality" units and rents are determined by limiting the full Census sample by including only responses meeting the following criteria:

a. Occupied rental units paying cash rent
b. Specified renter ? on 10 acres or less
c. with full plumbing
d. with full kitchen
e. built before 1999
f. meals not included in rent

"Recent Mover" rents are determined by further limiting the "Standard Quality" sample with the following additional criterion:

g. moved in within the last two years

A Microsoft Excel file containing the unsummarized versions of the publicly releasable recent mover and standard quality 2-bedroom rent distributions for Columbia County, WA is available here.

The 2000 Census did not include a question that could be used to filter public or assisted housing from the rental distributions, however HUD is required to ensure that FMRs exclude non-market rental housing in their computation. Therefore, HUD excludes all units falling below a specified rent level determined from public housing rents in HUD's program databases as likely to be either assisted housing or otherwise at a below-market rent (perhaps due to quality problems not otherwise captured by the Census questions). The "public housing" rent cut-off in Columbia County, WA is $323.


40th Percentile Recent Mover Rent

The following table and calculations demonstrate how the 40th percentile Census 2000 recent mover rent is determined for Columbia County, WA using the public distribution of recent mover rents for the county group specified above.

Portion of Recent Mover Rent Distribution Gross Rent Dollar Range Number of Units Percent of Eligible Distribution Cumulative Percent
Units below interval containing
public housing rent level of $323
$1 to $299 263 Not in Distribution Not in Distribution
Units in interval containing
public housing rent level of $323
$300 to $322 78.20 Not in Distribution Not in Distribution
$323 to $324 6.80 0.2% 0.2%
Units below interval containing
40th percentile recent mover rent of $503
$325 to $499 1,295 38.4% 38.6%
Units in interval containing
40th percentile recent mover rent of $503
$500 to $524 405 12.0% 50.6%
Units above interval containing
40th percentile recent mover rent of $503
$525 or more 1,668 49.4% 100.0%
Total units Above Public Housing Rent in Recent Mover Rent Distribution   3,374.80    

The numbers of units with recent mover rents above and below the Public Housing Rent level of $323 are determined using linear interpolation over the 85 units in the rent range $300 to $324. Linear interpolation uses the assupmtion that the 85 units' rents are uniformly distributed in the rent range around the Public Housing Rent level. Under this assumption, the proportion of the rent interval ($25) that is below the Public Housing Rent level is the same as the proportion of units with rents in the interval (85) that have rents below the Public Housing Rent level.

Proportion of rent interval below the Public Housing Rent Level: ($323 - $300) / $25 = 0.9200

Units in the Public Housing Rent Level Interval below the Public Housing Rent Level: 0.9200 x 85 = 78.20

The 40th percentile recent mover rent for Columbia County, WA is computed by linear interpolation over the 405 units in the rent range $500 to $524. Linear interpolation uses the assupmtion that the 405 units' rents are uniformly distributed in the rent range around the 40th percentile. Under this assumption, the proportion of the rent interval ($25) that needs to be added to the lower limit of the interval to reach the 40th percentile rent is the same as the proportion of units in the interval that needs to be added to the units in lower rent intervals to reach 40 percent of units in the distribution.

40 percent of units = 0.4 x 3,374.80 = 1,349.92

Units below the 40th percentile rent interval = 1,295.00 + 6.80 = 1,301.80

Units in 40th percentile rent interval needed to reach 40 percent of units = 1,349.92 - 1,301.80 = 48.12

Additional Units as Proportion of Interval = 48.12 / 405.00 = 0.1188

Dollars Added to Lower Limit of Interval to reach 40th percentile rent = 0.1188 x $25 = $3

40th percentile recent mover rent = $500 + $3 = $503


40th Percentile Standard Quality Rent

Before using the recent mover rent as the Census 2000 Base Rent, HUD checks the standard quality rent for the county group to ensure that the recent mover rent is high enough to reach the 40th percentile standard quality unit. The recent mover rent may be below the standard quality rent in areas where rental housing markets are particularly stressed such that recent mover rents will not cover the expenses of operating standard quality units.

The following table and calculations demonstrate how the 40th percentile Census 2000 standard quality rent is determined for the county group specified above using the public distribution of standard quality rents for the the county group.

Portion of Standard Quality Rent Distribution Gross Rent Dollar Range Number of Units Percent of Eligible Distribution Cumulative Percent
Units below interval containing
public housing rent level of $323
$1 to $299 520 Not in Distribution Not in Distribution
Units in interval containing
public housing rent level of $323
$300 to $322 133.40 Not in Distribution Not in Distribution
$323 to $324 11.60 0.2% 0.2%
Units below interval containing
40th percentile standard quality rent of $492
$325 to $474 2,050 33.6% 33.8%
Units in interval containing
40th percentile standard quality rent of $492
$475 to $499 545 8.9% 42.7%
Units above interval containing
40th percentile standard quality rent of $492
$500 or more 3,497 57.3% 100.0%
Total Units Above Public Housing Rent in Standard Quality Rent Distribution   6,103.60    

The numbers of units with standard quality rents above and below the Public Housing Rent level of $323 are determined using linear interpolation over the 145 units in the rent range $300 to $324. Linear interpolation uses the assupmtion that the 145 units' rents are uniformly distributed in the rent range around the Public Housing Rent level. Under this assumption, the proportion of the rent interval ($25) that is below the Public Housing Rent level is the same as the proportion of units with rents in the interval (145) that have rents below the Public Housing Rent level.

Proportion of rent interval below the Public Housing Rent Level: ($323 - $300) / $25 = 0.9200

Units in the Public Housing Rent Level Interval below the Public Housing Rent Level: 0.9200 x 145 = 133.40

The 40th percentile standard quality rent for Columbia County, WA is computed by linear interpolation over the 545 units in the rent range $475 to $499. Linear interpolation uses the assupmtion that the 545 units' rents are uniformly distributed in the rent range around the 40th percentile. Under this assumption, the proportion of the rent interval ($25) that needs to be added to the lower limit of the interval to reach the 40th percentile rent is the same as the proportion of units in the interval that needs to be added to the units in lower rent intervals to reach 40 percent of units in the distribution.

40 percent of units = 0.4 x 6,103.60 = 2,441.44

Units below the 40th percentile rent interval = 2,050.00 + 11.60 = 2,061.60

Units in 40th percentile rent interval needed to reach 40 percent of units = 2,441.44 - 2,062 = 379.84

Additional Units as Proportion of Interval = 379.84 / 545 = 0.6970

Dollars Added to Lower Limit of Interval to reach 40th percentile rent = 0.6970 x $25 = $17

40th percentile standard quality rent = $475 + $17 = $492

Since the standard quality rent of $492 is not higher than the recent mover rent of $503, the recent mover rent of $503 is the 2000 Census Base Rent for Columbia County, WA.



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Problems or questions? Contact Peter.B.Kahn@hud.gov.