# Presentation: 702128

## ACS PUMS – How to Aggregate Sample

- Anthony Tersine
- US Census Bureau
- State Data Center Meeting
- October 10, 2007

## ACS PUMS - Sampling

- 2005 PUMS is limited to housing units and household population
- 2006 PUMS includes housing units, household population and the group quarters population

## Multiyear PUMS Files	

- Two approaches – both combine single year files
- Adjust estimates at the end
- Adjust weights at the beginning

## Method 1

- Concatenate single year files
- Adjust dollar amounts for inflation
- Express prior year dollars in terms of latest year dollars

## Adjust Dollar Amounts – 1 

- First apply “ADJUST” variable within year
- Apply the CPI-U-RS adjustment factors from BLS
- _[http://www.bls.gov/cpi/cpiurs1978_2006.pdf](http://www.bls.gov/cpi/cpiurs1978_2006.pdf)_

## Adjust Dollar Amounts – 2 

- Express year 2005 dollars in terms of 2006 dollars
- Values from the CPI-U-RS table for 2005 (286.7) and 2006 (296.1)
- Multiply the 2005 dollars by 296.1/286.7 = 1.03279

## Adjust Dollar Amounts – Example 

- 2005-2006 person income in 2006 $
- 2005 person record
- PINC * (ADJUST / 1000000)  * 1.03279
- 2006 person record
- PINC * (ADJUST / 1000000)
- ADJUST – different values

## Method 1 –Tabulations

- Use combined file as a single-year file
- Adjust estimates based on number of years (M) combining
- Create counts, means, medians, etc.
- Create separate estimates for HU and GQ persons
- Standard Errors
- Replicate weights
- Generalized variances

##   Method 1 – Counts / Aggregates

- All years have GQs or only interested in HU or household pop

##   Method 1 – Counts / Aggregates

- Counts or aggregates - replicates
- Counts only - generalized

##   Method 1 – Counts / Aggregates

- Some (but not all) years have GQs
- M is total number of years
- N is the number of years with GQ data

##   Method 1 – Counts / Aggregates

- Counts or aggregates – replicates
- Counts – generalized

## Method 1 – Counts Example

| Estimate | 2005 | 2006 | 2005-2006 Total | 2005-2006 Period Est |
| --- | --- | --- | --- | --- |
| HU Population | 825,598 | 828,561 | 1,654,159 | 827,080 |
| GQ Population | NA | 24,915 | 24,915 | 24,915 |
| Males | 403,999 | 413,539 |  | 414,921 |
|    Males in HUs | 403,999 | 401,235 | 805,234 | 402,617 |
|    Males in GQs | NA | 12,304 | 12,304 | 12,304 |
| Females | 421,599 | 439,937 |  | 437,074 |
|    Females in HUs | 421,599 | 427,326 | 848,925 | 424,463 |
|    Females in GQs | NA | 12,611 | 12,611 | 12,611 |

- State of Delaware

##   Method 1 – Ratios

- All years have GQs or only interested in HU or household pop

##   Method 1 – Ratios

- Replicates
- Proportion/percents only - generalized

##   Method 1 – Ratios

- Some (but not all) years have GQs
- M is total number of years
- N is the number of years with GQ data

##   Method 1 – Ratios

- Replicates
- Proportion/percents only - generalized

##   Method 1 – Medians

- All years have GQs or only interested in HU or household pop
- Normal median (X) on the combined data
- Categorical median (Interpolated)

##   Method 1 – Medians

- Replicates
- Generalized – Can be done

##   Method 1 – Medians

- Some (but not all) years have GQs
- Use method 2

## Method 2

- Concatenate single year files
- Adjust weights
- Adjust dollar amounts for inflation
- Same approach as method 1

## Adjust Weights

- Adjustment factor is the                                               number of years being combined
- Divide by the factor

| Type of Record | 2005-2006 Period |  | 2005-2007 Period |  |  |
| --- | --- | --- | --- | --- | --- |
|  | 2005 Factor | 2006 Factor | 2005 Factor | 2006 Factor | 2007 Factor |
| HU Person | 2 | 2 | 3 | 3 | 3 |
| GQ Person | NA | 1 | NA | 2 | 2 |
| HU | 2 | 2 | 3 | 3 | 3 |
| GQ on HU | NA | NA | NA | NA | NA |

## Adjust Weights – Example 1

- 2005-2006 Estimate (PWGTP)
- 2005 HU person - weight 50 becomes 25
- 2006 HU person - weight 75 becomes 37.5
- 2006 GQ person - weight 60 will stay 60

## Adjust Weights – Example 2

- 2005-2007 Estimate (PWGTP)
- 2005 HU person - weight 67 becomes 22.333333
- 2006 HU person - weight 50 becomes 16.666667
- 2007 HU person - weight 75 becomes 25
- 2006 GQ person - weight 60 becomes 30
- 2007 GQ person - weight 55 becomes 27.5

## Contact Information

- _[Anthony.G.Tersine.Jr@census.gov](mailto:Anthony.G.Tersine.Jr@census.gov)_
- _[Alfredo.Navarro@census.gov](mailto:Alfredo.Navarro@census.gov)_