Data Collection MethodsIn Transportation Planning

Many data collection methods

• Customer satisfaction: http://www.dot.ca.gov/hq/maint/external_survey/2005_survey/index.htm

• Public involvement : http://www.101inmotion.com/

Data Collection Methods• Traffic monitoring: Loop

detector data (presence, speed, vehicle class)

• Used to provide historical records of use and real time information to motorists: http://www.dot.ca.gov/traffic/

• Traffic cameras: http://video.dot.ca.gov/

Travel SurveyQueen of Data Collection Methods

Design of a Survey• It is a process with many feedback

loops• Many choices depend on the reason

we collect data– Data as the base inventory– Data for models and simulations– Data for public involvement– Data for monitoring change (before-after)

• It is heavily influenced by time and money budgets

• Heavily quantitative but qualitative emerges as potentially powerful

• It reflects the designers model of society or explicit/implicit models of funding agencies

Survey ProcessRichardson-Ampt-Meyburg

Survey Methods for Transport PlanningEucalyptus Press

Human InteractionEmerging Research Direction in Travel

Behavior

Male, 40 years, full time worker, driver

Female, 36 years, home duties full time, driver

Male, 6 years, primary school

Male, 5 years, primary school

A family’s day in South Perth

Figure by Pribyl

Male, 47 years, full time worker, driver

Female, 42 years, home duties full time, driver

Female, 8 years, primary school

Male, 5 years, primary school

Another family’s day in

South Perth

Figure by Pribyl

10 Steps to Successful Surveys (Salant & Dillman)

• Understand and avoid the four kinds of error• Be specific about what information you seek

and why• Choose the survey method that will work

best• Decide whether and how to sample• Write good questions• Design and test the questionnaire• Assemble the necessary resources• Code, computerize and analyze the data• Present your results• Maintain perspective• Reports and presentations

Coverage Error• Occurs when the list (sampling

frame) from which the sample is drawn does not include all segments of the population that we want study/model

• The list used is not accurate and up-to-date

Sampling Error• Occurs because the survey

does not cover the entire population – it is not a census

• Always happens to some extent• Reduces by increasing the

sample size

Measurement Error• Occurs when a respondent’s

answer to a question is inaccurate, imprecise or in any other way unusable

• These errors come from— the survey method, the questionnaire, the interviewer, and the respondent

• Relatively easier for the researcher to control using statistical methods

Non-Response Error• Occurs when a significant

number of people in the sample do not respond to the questionnaire and are different from those that do in some way (this is also named selectivity bias in models)

• This is a main reason to maximize the response rate

Main Types of Surveys• Mail surveys• Telephone surveys• Face-to-face surveys• Internet surveys (immobile and

mobile)

When to Use Mail Surveys• You have a reliable address list• The people in the population

will respond accurately and completely by mail

• An immediate turnaround is not required

• Resources are relatively scarce but you have considerable amount of time

When to Use Telephone Surveys• The members of the population

are very likely to have telephones

• The questions are relatively straightforward

• Experienced help is available• A quick turnaround is

important

When to Face-to-Face Surveys• There is no list of the

population• You need to collect information

from people who are not likely to respond willingly or accurately by mail or telephone

• The questionnaire is complex• Well-funded projects• Experienced interviewers are

available

Maximize the Reward for Responding

• Show the respondent positive regard

• Give verbal appreciation• Use a “consulting” approach• Support the respondents

values• Offer tangible rewards• Make the questionnaire

interesting

Minimize the Cost of Responding

• Make the task appear brief• Reduce the physical and

mental effort required• Eliminate chances of

embarrassment• Eliminate any implication of

subordination• Eliminate any direct monetary

cost

Establish Trust With the Respondent

• Provide a token of appreciation in advance

• Identify with a known organization that has legitimacy

• Build on other exchange relationships

Schedule for the next few weeks

• Today (10/16/06)– Section survey type

• Next week (10/23/06)– Data collection methods part 2… components

of surveys. – Section broken into groups – Start writing questions

• 10/30/06– Issues with components, continue writing

questions

• 10/31/06 – Check for redundancy in survey (lecture)

• 11/3/06 (Friday) – Component due to me

Questions for reading about survey type• What is the Daily Reconstruction

Method (or Time Use Diary)?• What are the advantages of this

survey type?• What are the main categories or

sections (components) of the survey?

• Start thinking about how you would implement this technique in transportation (challenge: DRM in transportation setting, time use with attitudes and perceptions).

Write a 1 page MAX summary about your survey method with these questions in mind.

EMAIL TO ME BY THIS FRIDAY!!!!!!!