Production of Estimates and Projections

Census Bureau Principle
Version 1.2
Issued: 05 Jan 06

Authored for:
Census Bureau Methodology & Standards Council
Cynthia Z.F. Clark , Chair

Introduction

Survey estimation involves assigning values to unknown population parameters using information from data collected in the survey, and possibly from other sources. A direct survey estimator uses data collected on the variable of interest only from the time period of interest and only from sample units in the domain of interest. An indirect small-area estimator uses values of the variable of interest from a domain and/or time period other than the domain and time period of interest, and it may also incorporate information from other data sources, such as administrative records. A seasonal adjustment of a time series of estimates removes seasonality and calendar effects. A projection uses historical data, along with models and/or assumptions, to forecast or extrapolate future values.

Scope

These Principles apply to the calculation of direct survey estimates and indirect small-area estimates using data from sample-based surveys conducted by the Census Bureau, to the seasonal adjustment of monthly and quarterly times series of estimates, and to the calculation of population and related projections.

Principles

1. When using data from sample-based surveys to calculate direct survey estimates, the Census Bureau will use sample weights appropriate for the sample design. Sampling weights may be adjusted to reduce sampling or nonsampling errors. For example, the adjustment of sampling weights to handle nonresponse can reduce nonsampling error; whereas, the adjustment of sampling weights to handle unrepresentative outliers with large sampling weights can reduce sampling error. Auxiliary data and associated population totals will sometimes be used to improve precision and/or reduce nonsampling errors of direct survey estimates.
2. The Census Bureau sometimes produces estimates for geographic areas or subgroups of the population for which direct sample-based estimates would have inadequate statistical reliability, necessitating the development of indirect small area estimates. Models used and assumptions made for indirect small area estimates will be clearly documented to ensure objectivity, and appropriate statistical uncertainty measures will be provided where possible.
3. The Census Bureau performs seasonal adjustment of a time series of estimates only given clear evidence of seasonal behavior and only when the adjustment passes a suitable set of diagnostic tests. Diagnostics will be reviewed on a regular basis.
4. Projections forecast or extrapolate historical data, possibly using information from additional data sources. Models used, associated data sources, and assumptions made for projections will be clearly documented to ensure objectivity. Projections will be updated at suitable intervals based on new data.
5. Exemption from the requirements of these Principles may be sought in special circumstances using the procedure described below under “Responsibilities.”

Responsibilities

Program areas will be responsible for the following:

• Developing and evaluating methods for producing estimates or projections for their programs;
• Specifying seasonal adjustment program options and evaluation of the resulting adjustments, including determining whether or not a series should be seasonally adjusted;
• Developing requirements to satisfy these Principles in the design, schedule, and budget of new or re-designed statistical activities, programs, or products; and
• Submitting applications for exemption from the requirements of these Principles to the Census Bureau Methodology and Standards Council.

The Methodology and Standards Council will be responsible for the following:

• Providing standards and guidelines on the application of these Principles to program areas;
• Producing reports as necessary on the state of compliance with these Principles;
• Initiating evaluations of the application of these Principles within particular program areas and ensuring that such evaluations are co-ordinated with other program evaluation activities;
• Initiating a review of these Principles and accompanying standards and guidelines when deemed necessary; and
• Reviewing applications for exemption from the requirements of the Principles.

Inquiries

Inquiries relating to the interpretation of these Principles should be addressed to the Census Bureau Methodology and Standards Council.

Approved by Census Bureau Methodology and Standards Council:

                  Signed Cynthia Z.F. Clark, August 6, 2002  
                  Cynthia Z.F. Clark
                  Associate Director for Methodology and Standards
                  Chair, Methodology and Standards Council

                  Signed Robert N. Tinari, August 06, 2002
                  Robert Tinari
                  Chief, Computer Assisted Survey Research Office

                  Signed David Whitford, August 6, 2002
                  David C. Whitford
                  Acting Chief, Decennial Statistical Studies Division

                  Signed Al R. Tupek, August 6, 2002
                  Alan R. Tupek
                  Chief, Demographic Statistical Methods Division

                  Signed Howard Hogan, August 6, 2002
                  Howard Hogan
                  Chief, Economic Statistical Methods and Programming Division

                  Signed Ruth Ann Killion, August 6, 2002
                  Ruth Ann Killion
                  Chief, Planning, Research and Evaluation Division

                  Signed Tommy Wright, August 6, 2002
                  Tommy Wright
                  Chief, Statistical Research Division

Concurrence:

                  Signed Preston Jay Waite, June 11, 2003
                  Preston Jay Waite
                  Associate Director for Decennial Programs

                  Signed Nancy M. Gordon, June 11, 2003
                  Nancy M. Gordon
                  Associate Director for Demographic Programs

                  Signed Frederick T. Knickerbocker, June 11, 2003
                  Frederick T. Knickerbocker
                  Associate Director for Economic Programs

                  Signed Marvin D. Raines, June 11, 2003
                  Marvin D. Raines
                  Associate Director for Field Operations

                  Signed Gloria Gutierrez ,June 11, 2003
                  Gloria Gutierrez
                  Assistant Director for Marketing and Customer Liaison

                  Signed Cynthia Z.F. Clark ,June 11, 2003
                  Cynthia Z.F. Clark
                  Associate Director for Methodology and Standards

Document Management & Control

The most current version of this document is maintained on the Census Bureau Intranet and may
be accessed from the Quality Management Repository.

Category: Principle   
Filename: P07-0_v1.2 Estimates and Projections