information that allows estimates for certain expenditures to be made from either source, using different question wordings and time periods. BLS uses only data from a single source in its published estimates, selecting the “best” source for each item.
Approximately 7,100 interviews, each of which averages about 60 minutes, are conducted each quarter in the Interview survey, with five interviews for each household. Although most data are collected in household visits, an increasing proportion of the later interviews rely completely or partly upon telephone interviews. One-fifth of the sample is new each quarter, with a corresponding one-fifth of households completing the five-interview sequence. The Diary survey collects usable data from 7,100 households per year, each keeping two one-week diaries. Diary placements occur during 52 weeks of the year, with approximately 273 diaries being completed each week.
Most of the cost is associated with the Interview survey, which produces about 36,000 completed interviews per year, compared to about 14,000 one-week diaries. The “total” data collection cost for the CE surveys in 2010 was $21.2 million, with the Interview survey costing $17 million, or about 80 percent of the total.
THE PANEL’S INVESTIGATION
The panel received input from a wide variety of sources. Investigations conducted by the Gemini Project provided critical background. Several panel members themselves use CE microdata. The panel also reviewed published research and held a session at the 2011 CE Microdata Users’ Conference. The panel also studied the complexities of the CPI program and how the CE supports it.
Based on these investigations, the panel makes the following conclusions about the use of the CE. (The numbers represent the location of the conclusion in the full report; thus, more background on the conclusions below is in Chapter 4.)
Conclusion 4-1: The CPI is a critical program for BLS and the nation. This program requires an extensive amount of detail on expenditures, at both the geographic and product level, in order to create its various indices. The CPI is the current driver for the CE program with regard for the level of detail it collects. The CPI uses over 800 different expenditure items to create budget shares. The current CE supplies data for many of these budget shares. However, even with the level of detail that it currently collects, the CE cannot supply all of the budget shares used by the CPI. There are other data sources from which the CPI currently generates budget shares.