1. Calculating The Estimates And Weights For The Vacancy Rate Prepared for the 2010 SDC-CIC Joint Steering Committee Meetings February 24, 2010 Edward C. Castro Jr. U.S. CENSUS BUREAU U.S. DEPARTMENT OF COMMERCE Washington, DC 20233

2. 2 Outline Weighting Distribution of Vacant and Occupied Housing Units Vacancy Rate Summary

3. 3 Weighting Weights account for sampling the population. Initial weight accounts for probability of selection. Non-respondents for mail and telephone are sampled for follow-up. Non-interview adjustments controlled by geography, sample month, and type of home. Controls are applied to housing unit and population totals to correct coverage error.

4. 4 Distribution of Vacant and Occupied Housing Units Weighting StepDistribution Initial weight and non-respondents Vacant Housing Units Non- interviews Occupied Housing Units Non-interview Adjustment Vacant Housing Units Occupied Housing Units including Non-interviews Housing Unit Controls Vacant Housing Units Occupied Housing Units including Non-interviews

5. 5 Vacancy Rate Vacant Housing Units Non- interviews Occupied Housing Units Initial weight and non-respondents 8,000*2,00040,000 Non-interview Adjustment 8,000 Adjustment = (40,000 + 2,000) / 40,000 = 1.05 40,000 x 1.05 = 42,000 * Initial Vacancy Rate = 8,000 / 50,000 = 16%

6. 6 Vacancy Rate (cont.) Vacant Housing Units Occupied Housing Units Non-interview Adjustment 8,00042,000 Housing Unit Controls Total Housing Units = 50,000 Housing Unit Control = 51,500 Adjustment = 51,500 / 50,000= 1.03 8,000 x 1.03 = 8,240 42,000 x 1.03 = 43,260 Vacancy Rate = 8,240 / 51,500 = 16%

7. 7 Summary Vacancy rate is determined by sampling rate and non-response adjustment. There are adjustments for the non- interviews and housing unit controls but they do not impact the vacancy rate.

8. 8 Thank You If you have any questions or comments: Edward.C.Castro@census.gov For more information on the ACS please visit: http://www.census.gov/acs/www