Improving Accuracy in Household and External Travel Surveys

336 Pages·2010·4.55 MB·English

by  Texas Transportation Institute

Technical Report Documentation Page
1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
FHWA/TX-09/0-5711-1

4. Title and Subtitle 5. Report Date
IMPROVING ACCURACY IN HOUSEHOLD AND EXTERNAL August 2009
TRAVEL SURVEYS Published: January 2010

6. Performing Organization Code

7. Author(s) 8. Performing Organization Report No.
David Pearson, Edwin Hard, Stephen Farnsworth, Tim Forrest, Debbie Report 0-5711-1
Spillane, Mark Ojah, Katie Womack, Sharon Boxill, and Carol Lewis

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)
Texas Transportation Institute

The Texas A&M University System 11. Contract or Grant No.
College Station, Texas 77843-3135 Project 0-5711

12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered
Texas Department of Transportation Technical Report:
Research and Technology Implementation Office September 2006– August 2009
P. O. Box 5080

Austin, Texas 78763-5080
14. Sponsoring Agency Code

15. Supplementary Notes
Research performed in cooperation with the Texas Department of Transportation and the U.S. Department
of Transportation, Federal Highway Administration.
Research Project Title: Improving Quality and Accuracy in Select Travel Surveys
URL: http://tti.tamu.edu/documents/0-5711-1.pdf

16. Abstract
The Texas Department of Transportation has a comprehensive on-going travel survey program. This
research examines areas within two select travel surveys concerning quality control issues involved in data
collection and sampling error in the data caused by various assumptions, survey methods, and issues such as
non-response. Quality control issues, sampling errors, and non-response in external and household travel
surveys conducted in Texas are identified, examined, and evaluated. The impact of these issues is
quantified and evaluated relative to the use of the data in travel demand models. The state-of-the-practice in
these types of surveys relative to quality control during and after the surveys are conducted and how
sampling errors and non-response are treated (or corrected) in the survey analysis are reviewed and
documented. The results are assessed to formulate a set of recommendations for incorporating into survey
designs for the travel survey program.

17. Key Words 18. Distribution Statement
External Survey, Household Survey, Response No restrictions. This document is available to the
Rates, Survey Methodology, Geocoding, Data public through NTIS:
Analysis, Vehicle Classification Counts, Sample National Technical Information Service
Size, Survey Design Springfield, Virginia 22161
http://www.ntis.gov

19. Security Classif.(of this report) 20. Security Classif.(of this page) 21. No. of Pages 22. Price
Unclassified Unclassified 336
Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

IMPROVING ACCURACY IN HOUSEHOLD AND
EXTERNAL TRAVEL SURVEYS

by

David F. Pearson, Ph.D., P.E.; Research Engineer;
Edwin Hard, Research Scientist;
Stephen Farnsworth, Associate Research Scientist;
Tim Forrest, Assistant Transportation Researcher;
Debbie Spillane, Assistant Transportation Researcher;
Mark Ojah, Assistant Research Specialist; and
Katie Womack, Senior Research Scientist, of the Texas Transportation Institute

and

Sharon A. Boxill, Ph.D., Research Associate; and
Carol A. Lewis, Ph.D., Director, of Texas Southern University

Report 0-5711-1
Project 0-5711
Research Project Title: Improving Quality and Accuracy in Select Travel Surveys

Sponsored by the
Texas Department of Transportation
In Cooperation with the
U.S. Department of Transportation
Federal Highway Administration

August 2009
Published: January 2010

TEXAS TRANSPORTATION INSTITUTE
The Texas A&M University System
College Station, Texas 77843-3135

DISCLAIMER

The contents of this report reflect the views of the authors, who are responsible for the
facts and the accuracy of the data presented herein. The contents do not necessarily reflect the
official view or policies of the Federal Highway Administration (FHWA) or the Texas
Department of Transportation (TxDOT). This report does not constitute a standard,
specification, or regulation. The engineer in charge was David F. Pearson, P.E., (Texas,
#45457).

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ACKNOWLEDGMENTS

This project was conducted in cooperation with the Texas Department of Transportation
(TxDOT) and the Federal Highway Administration. The authors provide special thanks to Mr.
Charlie Hall, the TxDOT project director, for his guidance on this report and for his continuing
direction of the TxDOT‘s Travel Survey Program. The authors also acknowledge the
contributions the project monitoring committee, Bill Knowles and Greg Lancaster, both of
TxDOT‘s Transportation Planning and Programming Division, for their assistance during the
course of this project.

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TABLE OF CONTENTS

Page

List of Figures ............................................................................................................................... xi
List of Tables ............................................................................................................................... xv
Chapter 1: Introduction .............................................................................................................. 1
Background ................................................................................................................................. 1
Objectives and Significance of Research ................................................................................ 1
Research Approach ................................................................................................................. 2
Organization of Report ............................................................................................................... 3
Chapter 2: Survey Practices in Texas ......................................................................................... 5
Household Surveys ..................................................................................................................... 5
External Surveys ......................................................................................................................... 6
Survey Issues .............................................................................................................................. 7
Response Rates ....................................................................................................................... 7
Item and Unit Non-Response .................................................................................................. 7
Errors in Surveys..................................................................................................................... 9
Quality Controls .................................................................................................................... 10
Chapter 3: Household Surveys .................................................................................................. 11
Literature Review...................................................................................................................... 11
Household Participation ........................................................................................................ 11
Sampling Frames .................................................................................................................. 14
Non-Response ....................................................................................................................... 16
Incentives .............................................................................................................................. 20
Weighting and Expansion of Survey Data ............................................................................ 21
Survey Techniques ................................................................................................................ 22
Quality Control ..................................................................................................................... 23
Survey Geocoding ................................................................................................................. 24
Texas Practice ........................................................................................................................... 32
Household Participation ........................................................................................................ 32
Sampling Frames .................................................................................................................. 33
Non Response ....................................................................................................................... 34
Incentives .............................................................................................................................. 35
Weighting and Expansion of Survey Data ............................................................................ 35
Survey Techniques ................................................................................................................ 36
Quality Control ..................................................................................................................... 36
Survey Geocoding ................................................................................................................. 37
Summary ............................................................................................................................... 37
Household Survey Sampling Frame ......................................................................................... 38
Introduction ........................................................................................................................... 39
Methodology ......................................................................................................................... 39
Description of Data ............................................................................................................... 40
Data Analysis ........................................................................................................................ 41
Findings................................................................................................................................. 46
Non-Response in Household Surveys ....................................................................................... 47
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Introduction ........................................................................................................................... 47
Methodology ......................................................................................................................... 48
Description of Data ............................................................................................................... 48
Data Analysis ........................................................................................................................ 51
Summary of Findings ............................................................................................................ 60
Proxy Reporting in Household Surveys .................................................................................... 62
Background ........................................................................................................................... 62
Methodology ......................................................................................................................... 62
Description of Data ............................................................................................................... 64
Data Analysis ........................................................................................................................ 64
Summary of Findings .......................................................................................................... 176
Recommendations ............................................................................................................... 178
Chapter 4: External Surveys.................................................................................................... 181
Literature Review.................................................................................................................... 181
Survey Methodology ........................................................................................................... 181
Technology ......................................................................................................................... 182
Survey Design ..................................................................................................................... 183
Survey Sample Size ............................................................................................................ 184
Survey Conduct Times ........................................................................................................ 184
Vehicle Classifications in Surveys...................................................................................... 185
Survey Geocoding ............................................................................................................... 186
Survey Quality Control and Training ................................................................................. 186
Survey Data Entry and Checks ........................................................................................... 187
Expansion of Survey Data .................................................................................................. 188
External Surveys – Texas Practice .......................................................................................... 189
Overview ............................................................................................................................. 189
Survey Methodology ........................................................................................................... 190
Technology ......................................................................................................................... 191
Vehicle Classification Counts Performed in Conjunction with Surveys ............................ 192
Survey Geocoding. .............................................................................................................. 193
Survey Staffing, Quality Control, and Training .................................................................. 194
Survey Data Entry and Checks ........................................................................................... 198
Potential Improvements ...................................................................................................... 199
External Survey Vehicle Classification Counts ...................................................................... 201
Background ......................................................................................................................... 201
Analysis............................................................................................................................... 204
Summary of Findings .......................................................................................................... 205
Recommendations ............................................................................................................... 206
External Survey Directionality Evaluation ............................................................................. 219
Background ......................................................................................................................... 220
Methodology ....................................................................................................................... 220
Description of Data ............................................................................................................. 221
Data Analysis ...................................................................................................................... 221
External Survey Time-of-Day Evaluation .............................................................................. 233
Objective ............................................................................................................................. 233
Background ......................................................................................................................... 233
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Methodology ....................................................................................................................... 233
Analysis Results .................................................................................................................. 235
Findings............................................................................................................................... 235
Recommendations ............................................................................................................... 236
External Survey Sample Sizes ................................................................................................ 257
Objective ............................................................................................................................. 257
Background ......................................................................................................................... 258
Estimating Sample Size ...................................................................................................... 259
Assessing Impacts of Error Levels at Different Sampling Levels ...................................... 260
Estimating Potential Error Levels for Survey ..................................................................... 262
Description of Data ............................................................................................................. 264
Analysis Results .................................................................................................................. 267
Separate Non-Commercial and Commercial ...................................................................... 267
Combined Non-Commercial and Commercial ................................................................... 279
Recommendations ............................................................................................................... 286
External Survey Error Analysis .............................................................................................. 286
Objective ............................................................................................................................. 286
Background ......................................................................................................................... 287
Methodology ....................................................................................................................... 287
Tasks 1 and 2 – Literature Review and Texas Practice ...................................................... 287
External Survey Vehicle Classification Counts .................................................................. 292
External Survey Directionality Evaluation ......................................................................... 293
External Survey Time of Day Evaluation ........................................................................... 294
External Survey Sample Sizes ............................................................................................ 295
Summary and Recommendations ....................................................................................... 295
Summary and Recommendations ............................................................................................ 297
Household Surveys ............................................................................................................. 297
External Surveys ................................................................................................................. 298
Appendix A ................................................................................................................................ 301
References .................................................................................................................................. 315

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