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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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