College Road Trip: College Road Trip: Transforming the NHTS Transforming the NHTS

into a Web-Based Travel Diaryinto a Web-Based Travel Diary

A Survey of University Students

in Virginia

Presented at the AAPOR Annual Conference

May 15, 2010

Authors• Thomas M. Guterbock, UVA• Tancy J. Vandecar-Burdin, ODU• Susan G. White, VCU• Susan Willis-Walton, VT• Paul Agnello, VDOT• James M. Ellis, UVA• Deborah L. Rexrode, UVA• Wendi Wilson-John, ODU

About This Talk & Overall Issues

• Focusing on issues of adaptation vs. substantive results

• Change in the population being studied (from general household members to college students)

• Change of mode (from phone survey to web)

• Lengthy process

National Household Travel Survey

• Extensive transportation survey designed to collect travel behavior for all members of a household on a given travel day

• Landline Telephone Computer-Assisted Telephone Interviews (CATI)

• Includes a travel diary for all members of the household

• Respondents receive a $2 incentive• Follow-up 30-minute interview

Why NHTS Misses College Students• Travel behavior of college students

who live with parents may be independent from the household

• Off-campus students are less likely to respond

• Students in dormitories are excluded (group quarters)

• Landline numbers only; college students have mobile phones

Purpose of the University Supplement• VDOT requested 1,000 completions at

each of the four Virginia universities in order to:Adequately capture college-age student

travel behaviorDetermine if student travel behavior differs

significantly from the general populationAdd to the literature since no such study

has been done in VirginiaStudy universities that would be

representative for Virginia

TDM meets TDM

• Project was a collaboration of four universities and travel demand modeling experts from the universities, a consulting firm, and VDOT

• The survey researchers had to learn about travel demand modeling

• The travel demand modelers improved their knowledge of survey methodology

• An experience of "Tailored Design Method" encountering "Travel Demand Modeling"

Design Challenges• Trip purposes• Common travel modes• Unit of analysis• Coverage and reachability issues• Methods of motivating students• Survey mode• Presentation of travel diary• Assigning travel days• Capturing travel destinations

University of Virginia

• Located in Charlottesville, VA• Population of 41,487• MSA of 200,000• Current enrollment of 20,895• 57% live off-campus; 25.5% minority

VirginiaTech• Located in Blacksburg, Virginia• Population of 40,000• A land grant university with a sprawling

campus of 2,600 acreas• Enrollment of 28,432• 62% live off-campus; 29.6% minority

Old Dominion University• Located in Norfolk, Virginia• Urban area of 233,000 in a region of

1.6 million• Enrollment of 24,013 (4 campuses)• 73% live off-campus; 31% minority

Virginia Commonwealth University

• Located in the capital city of Richmond

• Urban area of 200,000 in a region of 1.2 million

• Enrollment of 32,436 (2 campuses)

• 78% live off-campus; 36% minority

Urban commuter campus vs. Residential campus in college town

• Expected lower response rates at urban universities

• Larger sampling frame at urban universities

• Tested in-class recruitment protocols at one urban school

• Residential universities developed pre-coded lists of destinations

Conceptualization

• NHTS is centered on trips to and from work and trips to and from schools for children in grades K-12

• The work of college students is going to school• Trips for purposes such as employment or

extra-curricular activities are more like trips parents make to schools in the NHTS

• NHTS questions about commuting to work were adapted to ask about the daily trip to the university

What is a Trip?

Trip Origin Mode Destination

1 Home RemoteParking

2 RemoteParking

School

3 School Gym

4 Gym Home

Unit of Analysis• NHTS uses “household” – every member

completes a trip diary and all trips are counted

• For college students – “household” is problematicSampling frame = individuals vs. householdsRoommates/dorm mates vs. household

membersCannot assume vehicles are sharedSome students do live in family households

Reachability & Coverage• Difficulties reaching college students:

Current local addresses & telephone numbers not updated

University often given permanent/parental contact information instead of that for the student

Universities relying more on email as main communication method

Web-based survey via email invitations agreed upon as best method at the time

Reachability & Coverage, cont.• Problems with out-of-date contact

information: Addresses: missed hard copy study info/travel

diary & $3 incentive for UVA studentsTelephone: missed follow-up reminders or

messagesParents as messengers?Not checking/maintaining university email

account = missed email invitation/reminders

Incentives

University Incentive MethodUniversity of Virginia (UVA) $3 incentive included with

advanced letters to all sampled students

Virginia Tech (VT) Lottery for $300 gift cardVirginia Commonwealth University (VCU)

Lottery drawing for gift cards of $500, $200, $100, $50, $20, and $10

Old Dominion University (ODU)

Lottery drawing for (15) $500 gift cards & (20) $100 gift cards

Diary Visualization & Web Implementation

• Hard copy travel diary as a memory aidNot feasible to have identical travel diary in

the web survey

• Pre-coded/drop down lists of destinations/trip purposes (campus building and parking lots)

• Off-campus location lists also available for students at UVA and VT

Travel Day Assignment• Travel days randomly assigned at each

University – two different protocols:“Yesterday, web only” (VT)“Set date, postal/web” (ODU, UVA, VCU)

• Non-respondents given re-assigned travel days – same day of the week as original travel dayUp to (3) re-assigned travel days for VT students(1) re-assigned travel day for ODU, UVA, VCU

students

Number of Trips & Completeness of Trip Diaries

The case of too many “one-trippers” (20%)

• Qualitative follow-up with respondents who only reported one trip

• Going to campus or other destinations but never returning home

• Problems with verification question

Resolving the“One-tripper” Issue• Reviewed data, open-ended comments

to determine legitimate “one-trippers”

• Other “one-trippers” deleted – did not differ demographically from other respondents

• Still retained about 4,000 trips per

University for analysis/geocoding

Destinations• Students lack of knowledge re: street

addresses vs. need to geocode every destination

• National NHTS telephone interviewers have GIS capability to confirm address

• Pre-coded lists – more extensive for UVA and VT

• Students able to pick from list or provide street address or other information (e.g., cross streets, business name)

Implementation & Effort Required• Unusual burdens compared to “typical”

web surveyAction required every day of the study

periodRandom assignment of travel days & pre-

survey postal mailings and email invitation timing

Email invitations, reminders and/or re-assigned travel emails sent every day

Telephone reminders also started within the first week of the study period

Representativeness of the Sample

UniversityDemographicCharacteristic

University Student Population Survey

Respondents

Virginia Tech (VT)

MaleFemale

57.2%42.8%

48.2%51.8%

White Black

70.6%3.8%

66.0%1.3%

Full-timePart-time

96.1%3.9%

99.6%0.4%

UndergraduateGraduate

82.7%16.0%

57.5%41.9%

Old Dominion University (ODU)

MaleFemale

42.1%57.3%

37.8%62.2%

WhiteBlack

60.1%20.4%

67.0%16.0%

Full-timePart-time

76.8%23.2%

80.3%19.7%

UndergraduateGraduate

82.0%18.0%

73.7%24.8%

Response Rate

UniversityNumber of Students

Contacted (Eligible)

Number of Completed

SurveysResponse

RateUniversity of Virginia (UVA)

2,407 1,003 41.7%

Virginia Tech (VT) 3,630 1,039 28.6%Old Dominion University (ODU)

5000 962 19.2%

VCU sent 15,000 students an e-mail invitation and 1,509 (10.1%) students expressed interest and were sent survey packets. Of the 1,509 students interested, 756 (50.4%) completed the survey.

Codability

UniversityPercent of Trip

Destinations Coded

University of Virginia (UVA) 88.4%

Virginia Tech (VT) 80.0%

Virginia Commonwealth University (VCU) 94.3%

Old Dominion University (ODU) 95.0%

Utility of the Data

Cost and Effort• An unusual amount of effort was required

to manage a study of this magnitude• Multiple stages and layers of

communication with respondents versus the traditional web survey

• Research center staff obtained a daily list of completes from VTCSR.

• Follow-up reminder phone calls were often more involved than typical reminder phone calls.

Virginia Tech’s Follow-Up Study

• VDOT wanted to further explore the issue of the “one-trippers”.

• A number of changes were made to the survey instrument: Abbreviated survey instrumentRedesign of graphic depicting travel day and trip

examplesWording revisions to clarify questions and make

response categories better suited to the trip informationProgramming checks were added which prompted

students to explain if they reported no trips or only one trip for their travel day.

Follow-Up Study Results• 1,032 Virginia Tech students participated

in the follow-up survey.• Improved clarity of the desired travel

information obtained from respondents• Only 27 respondents reported taking

zero or one trip on their travel day compared to 20% in the fall study at the four universities.

Overall Conclusions

• Ultimately succeeded with providing VDOT a rich set of travel data.

• Able to adapt the survey from a phone methodology and obtain usable information via a web survey.

• Cost and effort of a large scale web survey should not be underestimated.

Future Research• A full study to determine whether the omission

of the advance diary mailing really has no adverse effect on reporting quality.

• A full-scale study of a telephone approach versus a web-based approach at the same university

• A split-ballot experiment in which sampled students are randomly assigned to respond using one or the other of the two different trip definitions.