Can the Census Bureau estimate the effect of Hurricanes Katrina and Rita on the sales estimates?
No. We cannot isolate the effect of Hurricanes Katrina and Rita on the Advance Monthly Retail Trade and Food Services Survey (MARTS) estimates since the sample is designed to measure retail and food services activity at the national level and not at specific geographic areas.
Even though we cannot isolate the effect, we did receive indications from the companies that the hurricanes had both positive and negative effects on the retail sales data. Some firms reported a drop in sales due to permanent or temporary store closures and stores having reduced business due to damage, fewer customers, and/ or lack of employees. On the other hand, some firms reported sales increases due to significant sales of supplies for the affected areas and evacuees purchasing retail and food services in different geographic locales.
The areas most affected by the hurricanes ordinarily account for a minimal percentage of total U.S. retail and food services sales based on the 2002 Economic Census. See http://www.census.gov/econ/census02/guide/Hurricanes.HTM for data from the 2002 Economic Census for the Gulf Coast areas affected by Hurricanes Katrina and Rita.
Can the Census Bureau produce monthly retail and food services sales estimates for the affected areas?
No. We cannot separately estimate retail sales for the affected areas since the MARTS sample is designed to estimate sales for the national level only.
Was the Census Bureau able to collect information from firms operating within the affected areas?
Yes. In Louisiana, Mississippi, and Alabama, 92 firms responded with sales data. Over the previous six months, we received between 88 and 103 reports from these states. In Texas, we received 201 reports with sales data. This compares to a usual range between 185 and 201 in the previous six months. Further, many large, regional, and other multi-location firms with reporting offices outside the affected states responded at a normal rate and included sales data for stores, both open and closed, located in the affected areas. For the entire survey, we received 3,162 responses this month, which compares favorably to the six-month range of 3,061 to 3,199.
Did the Census Bureau modify its non-response or estimation procedure?
No. Ordinarily, no imputation is done for individual nonrespondents. The MARTS survey accounts for missing data when estimating industry totals. The estimate makes use of data from MARTS respondents that report sales data for both August and September and applies the resulting month-to-month change to the August sales estimates from the Monthly Retail Trade Survey (MRTS). The MRTS imputes missing data for nonresponding firms based on reported data from firms that are in the same industry and the same size category as the nonrespondents.
The estimation procedure assumes that for a given industry the month-to month change for firms that report is similar to the month-to-month change for firms that do not report. This assumption is supported if sufficient reports from the affected area are received or if the reports received are representative of the area.
Retail sales for the most affected area are ordinarily a small percentage of the national total, so any bias that may be incurred because sales for responding firms are substantially different from sales for nonresponding firms will be negligible in the context of the Nation's total sales. As part of our review, we evaluated the effect of nonresponse on the national totals and felt no change to the methodology was necessary.
Has the reliability of the sales estimate changed because of the hurricanes?
No, the reliability has not changed substantially. Most firms in the sample were able to report sales for September (see previous FAQ). At the national level, reported sales for September exhibited variation similar to that for prior months. A few individual firms reported large increases or decreases in their sales because of the effects of the hurricanes, but this additional variation was not large enough to affect the reliability of national estimates.
Did the Census Bureau alter the seasonal adjustment options for the month?
No. The review of the seasonal adjustment output and diagnostics did not indicate that adjustments to the options were necessary for this month.
Did the Census Bureau change its analytical procedures this month?
Yes. In addition to the usual analysis done every month, we reviewed independent data sources and discussed the effects of the hurricanes with companies on the survey.
What activities is the Census Bureau planning to ensure the affected areas will continue to be accurately represented?
During our data collection, we will continue to ask questions that will help us monitor impacts from the affected areas as part of our regular telephone follow-up. We will monitor data responses and make adjustments if necessary.
Source: U. S. Census Bureau
Service Sector Statistics Division
Last Revised: October 13, 2005