ACS 2005 Standard Quality Rent Calculation for
Mariposa County, CA

The following information provides details on how the 2005 ACS Standard Quality Median Rent of $835 and the 2000 Census Standard Quality Median Rent of $640 and the update factor of 1.3047 was developed for Mariposa County, CA using the publically releasable distributions for California.

The distributions shown below are constructed by removing the counts of ACS-1 and ACS-2 areas from the total state distributions.

User Note

In computing state based standard qualtiy 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 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.


Standard Quality Rents

HUD uses rents for standard quality units to generate update factors. "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

Neither the 2000 Census not the 2005 ACS included 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 survey questions).

The "public housing" rent cut-off in California in 2005 is $358 and the 2000 cut-off rent is $323.

A Microsoft Excel file containing the unsummarized versions of the publicly releasable standard quality 2-bedroom rent distributions from the 2005 ACS for California, excluding ACS-1 and ACS-2 areas, is available here.

A Microsoft Excel file containing the unsummarized versions of the publicly releasable standard quality 2-bedroom rent distributions from the 2000 Census for California, excluding ACS-1 and ACS-2 areas, is available here.


50th Percentile 2005 ACS Standard Quality Rent - California

The following table and calculations demonstrate how the 50th percentile 2005 ACS standard quality rent is determined for California using the public distribution of standard quality rents for the state.

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 $358
$0 to $349 9,215 Not in Distribution Not in Distribution
Units in interval containing
public housing rent level of $358
$350 to $357 155.20 Not in Distribution Not in Distribution
$358 to $374 329.80 0.3% 0.3%
Units below interval containing
50th percentile standard quality rent of $790
$375 to $774 57,140 47.0% 47.3%
Units in interval containing
50th percentile standard quality rent of $790
$775 to $799 5,555 4.6% 51.9%
Units above interval containing
50th percentile standard quality rent of $790
$800 or more 58,520 48.1% 100.0%
Total Units Above Public Housing Rent in Standard Quality Rent Distribution   121,544.80    

The numbers of units with standard quality rents above and below the Public Housing Rent level of $358 for California are determined using linear interpolation over the 485 units in the rent range $350 to $374. Linear interpolation uses the assupmtion that the 485 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 (485) that have rents below the Public Housing Rent level.

Proportion of rent interval below the Public Housing Rent Level: ($358 - $350) / $25 = 0.3200

Units in the Public Housing Rent Level Interval below the Public Housing Rent Level: 0.3200 x 485 = 155.20

The 50th percentile standard quality rent for California is computed by linear interpolation over the 5,555 units in the rent range $775 to $799. Linear interpolation uses the assupmtion that the 5,555 units' rents are uniformly distributed in the rent range around the 50th 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 50th 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 50 percent of units in the distribution.

50 percent of units = 0.5 x 121,544.80 = 60,772.40

Units below the 50th percentile rent interval = 57,140.00 + 329.80 = 57,469.80

Units in 50th percentile rent interval needed to reach 50 percent of units = 60,772.40 - 57,470 = 3,302.60

Additional Units as Proportion of Interval = 3,302.60 / 5,555 = 0.5945

Dollars Added to Lower Limit of Interval to reach 50th percentile rent = 0.5945 x $25 = $15

50th percentile standard quality rent = $775 + $15 = $790

The difference between the actual 2005 ACS Standard Quality Rent of $835 and the demonstration 2005 ACS Standard Quality Rent of $790 computed here is due to the effects of rounding on the public distribution as described above.


50th Percentile Standard Quality Rent - California

The following table and calculations demonstrate how the 50th percentile Census 2000 standard quality rent is determined for California using the public distribution of standard quality rents for the state.

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 7,185 Not in Distribution Not in Distribution
Units in interval containing
public housing rent level of $323
$300 to $322 1,584.24 Not in Distribution Not in Distribution
$323 to $324 137.76 0.1% 0.1%
Units below interval containing
50th percentile standard quality rent of $645
$325 to $624 57,363 46.5% 46.6%
Units in interval containing
50th percentile standard quality rent of $645
$625 to $649 5,367 4.3% 50.9%
Units above interval containing
50th percentile standard quality rent of $645
$650 or more 60,578 49.1% 100.0%
Total Units Above Public Housing Rent in Standard Quality Rent Distribution   123,445.76    

The numbers of units with standard quality rents above and below the Public Housing Rent level of $323 for California are determined using linear interpolation over the 1,722 units in the rent range $300 to $324. Linear interpolation uses the assupmtion that the 1,722 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 (1,722) 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 1,722 = 1,584.24

The 50th percentile standard quality rent for California is computed by linear interpolation over the 5,367 units in the rent range $625 to $649. Linear interpolation uses the assupmtion that the 5,367 units' rents are uniformly distributed in the rent range around the 50th 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 50th 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 50 percent of units in the distribution.

50 percent of units = 0.5 x 123,445.76 = 61,722.88

Units below the 50th percentile rent interval = 57,363.00 + 137.76 = 57,500.76

Units in 50th percentile rent interval needed to reach 50 percent of units = 61,722.88 - 57,501 = 4,222.12

Additional Units as Proportion of Interval = 4,222.12 / 5,367 = 0.7867

Dollars Added to Lower Limit of Interval to reach 50th percentile rent = 0.7867 x $25 = $20

50th percentile standard quality rent = $625 + $20 = $645

The difference between the actual 2000 Census Standard Quality Rent of $640 and the demonstration 2000 Census Standard Quality Rent of $645 computed here is due to the effects of rounding on the public distribution as described above.


Computing the 2000 - 2005 State Standard Quality Update Factor - Mariposa County, CA

The 2000 to 2005 update factor is calculated as the ratio of the 2005 ACS standard quality median rent to the 2000 Cesus standard quality median rent for California. Therefore the 2000 - 2005 update factor is:

= 2005 Standard Quality Median Rent / 2000 Standard Quality Median Rent

= $790 / $645

= 1.2248

The difference between the actual 2000 - 2005 update factor of 1.3047 and the demonstration update factor of 1.2248 computed here is due to the effects of computational rounding and the use of the rounding performed on the public distributions as described above.



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