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Second Day Response Rates: . Implications for CMAP’s Travel Tracker Survey. 13th TRB Planning Applications Conference, Reno. Cemal Ayvalik and Eric Petersen. May 12, 2011. Introduction. Many MPOs implement 2-day travel surveys Benefits:

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second day response rates

Second Day Response Rates:

Implications for CMAP’s Travel Tracker Survey

13th TRB Planning Applications Conference, Reno

Cemal Ayvalik and Eric Petersen

May 12, 2011

introduction
Introduction
  • Many MPOs implement 2-day travel surveys

Benefits:

  • Statistical insights at a lower cost than surveying twice as many households.

Risks:

  • Significant day-to-day variation in individual travel:
    • major activities at the tour level,
    • number of stops and duration,
    • scheduling of activities,
    • mode shifts
    • and route choice.
  • Respondent fatigue likely to bias the results.
measuring fatigue
Measuring Fatigue

Clues for response fatigue.

  • Stop activities may be omitted on second day.
  • Work tours may be less affected than other travel purposes.
  • Issues possible in full chain of activities or omissions in maintenance or leisure activities on the second day.
  • Markers that might raise flags or minimize concern.
    • The respondent actually indicates whether the data is being read off hard copies of a travel diary or reported from memory.
    • One respondent providing information on all household members.
correcting for response fatigue
Correcting for Response Fatigue
  • Depending on the severity of the problem, there are a variety of options:
    • Discarding the entire record;
    • Discarding the second day and treating the first day as if it were one-day data;
    • Reweighting either the second day or both days;
    • Adjusting the existing data with respect to VMT or activity duration;
    • Synthesizing missing information.
  • However, modelers must know extent of the problem before making any adjustments or corrections.
case study chicago metropolitan area
Case study: Chicago Metropolitan Area
  • In the 2008Travel Tracker household survey conducted for the Chicago Metropolitan Agency for Planning (CMAP):
    • More than 14,300 households, 10,000+ in 6-County Area.
    • About 30 percent of households in 6-County area were asked about their travel activities over 2 days (over 3,100 households).
    • The rest responded via one-day travel diaries.
  • Is respondent fatigue an issue that leads to degradation in the data outweighing the advantage of 2-day surveys?
tour level observations
Tour Level Observations
  • Diaries from Typical Travel Day
  • Weekdays
  • Home-Based complete tours
  • Adults, Age 16 or Over
  • Work vs. Non-Work Tours
testable hypotheses
Testable Hypotheses
  • Hypothesis #1: Will respondent fatigue decrease the tour count and number of stops by tour type reported in 2-day surveys ?
  • Hypothesis #2: Will respondent fatigue decrease the tour count and number of stops by tour type reported on the second day?
  • Hypothesis #3: Will respondents reading from travel diaries suffer less fatigue?
  • Hypothesis #4: Will respondent fatigue increase as the number of household members increases?
tour level comparisons
Tour Level Comparisons
  • Reduction in number of tours and stops in tours is considered as an indicator of response fatigue.
  • Tours in the first day of 2-Day survey and the 1-Day survey are compared first.
  • Differences between the days in 2-Day survey were analyzed.
  • Completion of a log, household size and survey type are used as explanatory variables.
  • Number of tours and number of stops in a tour for work and non-work tours were dependent variables.
tour level comparisons1
Tour Level Comparisons

1-Day vs. 2-Day Surveys

tour level observations3
Tour Level Observations

First vs. Second Day in 2-Day Survey

summary of results
Summary of Results
  • Two different types of fatigue can be evaluated:
    • Fatigue across survey types (mix of single and multi day diaries).
    • Fatigue across survey days within multi-day surveys.

Based on trip comparisons:

  • Less travel is reported by 2-day survey.
  • Less travel is reported on second day of 2-day survey.
  • Mandatory travel similar on first and second day.
  • Fewer non-mandatory stops on the second day.
summary of results1
Summary of Results

Based on tours:

H1:

  • Equivalent number of tours reported by survey type.
  • Fewer non-mandatory tours in the 2-day survey.
  • Complexity of mandatory tours seems to be increasing in 2-day survey.
    • Are shorter non-mandatory tours condensed into longer mandatory tours in reporting or is it due to day-to-day variation?

H2:

  • No major differences between first and second day.
  • More mandatory tours reported in first day.
summary of results2
Summary of Results

H3:

  • Shorter tours were observed from respondents who did not fill out a travel log.
    • The reason why they did not fill a diary is unknown. May be fatigue or the travel activity was actually short enough to recite from the memory.

H4:

  • Larger households - higher tour count and more stops
  • Three-person households had unique patterns
    • More work tours
    • Primarily due to differences in member relationships and composition.
next steps
Next Steps
  • Day-to-day variation.
  • Unclear whether this is non-random.
  • Use GPS data to establish a degree of day-to-day variation.
  • Looking at the variation by different segments including:
    • household life cycles,
    • time of day,
    • activity patterns (linked activities, tours by complexity),
    • geography, and
    • data retrieval methods.
  • Matched-Pair Design to control for socioeconomics.
  • Model tour types and lengths using 1-Day survey data.
  • Cross-validate using 1-Day and 2-Day survey data.
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