answer young people just like old people? impacts and ...answer young people just like old people?...

KIT – University of the State of Baden-Wuerttemberg and

National Research Center of the Helmholtz Association www.kit.edu

INSTITUTE FOR TRANSPORT STUDIES

Answer Young People Just Like Old People? – Impacts and Consequences of Different Household Travel Survey Methods Dr.-Ing. Martin Kagerbauer

7 March 2013 New Techniques and Technologies for Statistics (NTTS), Session 17C: Special session on COST/Shanti, Brussels

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Answer Young People Just Like Old People? – Impacts and Consequences of Travel Survey Methods

New Techniques and Technologies for Statistics (NTTS), Brussels Institute for Transport Studies

Agenda

Background of the survey

Different methods of the survey

Comparison of the different survey methods

Response rates, sample sizes, types of households, car-ownership, age, profession, season tickets for public transport

Mobility key figures, modal split and trip purpose

Conclusion and Outlook

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Region of Stuttgart

Conurbation of 179 cities and boroughs

A total of about 2.7 million inhabitants

Household Travel Survey

5,500 households

Multi-day survey

Duration one week

Objectives of the Survey

Update the mobility database

Input for a transport demand model (microscopic and macroscopic)

Information about variability and stability of travel behaviour

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Data collected during the survey

Socio-demographic data concerning the household and all persons living in the household

Trip data with location of origin and destination (transferred into geocodes)

Survey is based on German Mobility Panel (MOP) and combines other survey designs

Sample size

Verification

Sample

Main

Sample

Methode for large

sample size

Check against MOP

Regional Data MiD, ...

Quality assurance Efficiency

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Sample size

Verification Sample approx. 1,000 HH

Main Sample approx.

4,500 HH

PAPI method (paper-pencil-interview)

following the design of the German Mobility Panel

CAWI-method (computer-assisted-

web-interview)

CATI-method (computer-assisted-

telephone-interview)

Survey methods

A lot of questions „Only“ questions required for modelling

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PAPI method (Paper-Pencil-interview)

Household and person questionnaire (e.g. number of persons/children living in the household, number of cars, information about the cars, parking situation, public transport situation , sex, age , profession, car and public transport availability etc.)

Trip diary (start and end time of trip, modes used, trip purpose, duration, trip length)

Questionnaire is sent back by mail and plausibility checked

Design based on German Mobility Panel (MOP)

Allows benchmarking without methodological differences

Time-tested method and common practice in Germany

The PAPI-sample serves as verification sample in the comparison of the different survey methods

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CATI method (computer-assisted-telephone-interview)

Participants are asked to report their trips by phone

All participants are called two or three times during the survey period and asked to report their trips

Trips are entered into the computer directly

The data is immediately plausibility checked

In case of mistakes in the data, interviewer can ask participants immediately to clarify

Disadvantage: Participants can forget some trips in the haste of a telephone call

Innovative method in multi-day surveys but common practice in cross-sectional surveys in Germany

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CAWI method (computer-assisted-web-interview)

Participants report their trips via internet in a software tool

Data is checked one day at a time

In case of mistakes, participants are contacted and asked to give missing information

Participants can take part in the survey at any time they want

Disadvantage: Participants do not answer very thoroughly

Innovative method in multi-day surveys tested in cross-sectional surveys in Germany

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Survey procedure

Total sample size (5,500 Households)

Households are randomly drawn (registration offices)

Only mailing address provided

Merge telephone numbers, if possible

Verification Sample (1,000 Households)

Main Sample (4,500 Households)

Random division of the total sample to two subsamples

Contacting the participants

First contact by mail, introducing the survey and asking to participate

When phone number available: another contact by phone (this generally leads to higher response rates than only mail)

Participant can choose between CATI and CAWI-methode

CATI-Sample CAWI-Sample

Questionnaires Memory jogger and calls Web access

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Response rates

CATI+CAWI very similar to PAPI

CATI CAWI CATI+CAWI PAPI

Ratio of households successfully surveyed [%]

(=useful questionnaires / sample size)8.1% 8.8%

Ratio of households willing to participate [%]

(=households willing to participate / sample size)16.7% 15.1%

Ratio of households successfully surveyed [%]

(=useful questionnaires / households willing to participate )64.1% 39.7% 51.8% 63.0%

Response ratesStuttgart Region Survey 2009

Not applicable due to

the survey method

Not applicable due to

the survey method

In CATI more of the households willing to participate actually take part in the survey then in CAWI

Participants in CATI are more reliable

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Types of households

Overall comparison between PAPI and CATI+CAWI is similar

CATI CAWI CATI+CAWI PAPIALL

(CATI+CAWI+PAPI)

Sample size [housholds] 2,215 2,250 4,465 1,096 5,561

Single household 7.1% 12.2% 9.7% 8.0% 9.4%

Couple household without children 11.2% 22.0% 16.7% 20.0% 17.3%

Family or single parent household with children < 19 years 19.6% 33.9% 26.8% 25.5% 26.5%

Senior household 49.7% 17.5% 33.5% 28.2% 32.4%

Multi-person-household without children < 19 years 12.5% 14.4% 13.4% 16.8% 14.1%

No classification 0.0% 0.0% 0.0% 1.6% 0.3%

Types of households

Stuttgart Region Survey 2009

Share of senior households high in CATI and very low in CAWI.

Share of single, couple and single parents households high in CAWI and very low in CATI

Seniors are available by telephone and not so familiar with technology

Single persons and couples without children are hard to reach by phone but more familiar with internet

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Age of the persons

CATI: High share of elderly and smaller share of younger people (19 to 34 years)

CAWI: Smaller share of elderly and high share of teens and middle aged people

PAPI: Gap between people with 19 to 34 years (less) and 35 to 64 years (more)

Results for CATI+CAWI compared with PAPI method are similar

It is difficult to reach elderly people with the CAWI method and similarly difficult to reach the age group between19-34 for CATI


(CATI+CAWI+PAPI)

Sample size [persons] 5,166 6,149 11,315 2,852 14,167 2,679,000

0 to 18 years 20.3% 27.2% 24.0% 23.6% 23.9% 18.8%

19 to 34 years 8.7% 15.6% 12.5% 11.3% 12.2% 19.6%

35 to 64 years 38.3% 46.5% 42.7% 46.7% 43.5% 41.9%

65 years and older 32.7% 10.7% 20.8% 17.5% 20.1% 19.7%

Not specified 0.0% 0.0% 0.0% 1.0% 0.2% 0.0%

Age

Stuttgart Region Survey 2009 Stuttgart Region

population

parameter

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Profession of the persons

CATI: High ratio of retired persons and low ratio of fully working people

CAWI: Low ratio of retired persons and high ratio of fully working people

PAPI: Similar to CATI+CAWI

Only CAWI and CATI represent all professions primarily the fully working and the retired people


(CATI+CAWI+PAPI)

Sample size [persons] 5,166 6,149 11,315 2,852 14,167

Fully working 22.2% 32.8% 28.0% 29.2% 28.2%

Partly working 10.8% 13.6% 12.3% 14.1% 12.7%

Not working/ jobless 6.2% 7.7% 7.0% 7.6% 7.1%

In education 18.8% 23.9% 21.6% 23.9% 22.1%

Retired person 35.9% 11.9% 22.9% 19.5% 22.2%

Not specified 6.1% 10.1% 8.3% 5.8% 7.8%

Profession


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Mobility key figures

Lower share of trip makers and lower amount of kilometers per day in CATI due to higher ratio of elderly persons

No significant differences between the methods for the trips per person

Number of kilometers per day and the time spent for transport are higher in CAWI than in CATI (as a follow: different levels of speed and trip length)


(CATI+CAWI+PAPI)

Sample size [person-days] 34,496 39,585 74,081 16,653 90,734

Trip makers [%] 84% 87% 86% 90% 87%

Trips per person and day [no] 3.0 3.1 3.0 3.1 3.0

Kilometres per person and day [km] 29.5 34.9 32.3 35.3 32.9

Minutes per person and day [min] 74 77 76 72 75

Average speed [km/h] 24.1 27.0 25.7 29.4 26.4

Average trip length 9.9 11.4 10.7 11.2 10.8

Mobility key figures


T-test: Kilometers and travel time differ significantly between the methods

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Modal Split

Similar results for all survey methods

Small difference for “foot”: Share is higher for CATI method


(CATI+CAWI+PAPI)


Foot 27.6% 22.9% 25.0% 22.3% 24.5%

Bike 4.3% 5.5% 4.9% 4.6% 4.9%

Motorcycle and car as driver 42.6% 44.1% 43.5% 47.2% 44.1%

Car as passenger 13.8% 13.4% 13.6% 13.2% 13.5%

Public Transport (Bus, rapid transit) 10.5% 12.3% 11.4% 10.6% 11.3%

Railway 1.1% 1.6% 1.4% 1.8% 1.5%

Others 0.1% 0.2% 0.2% 0.3% 0.2%

Modal split


Methodical effect : In a telephone interview, the interviewer can immediately ask about forgotten trips, especially short trips made by foot

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Trip Purpose

Combination of CATI+CATI show similar results as PAPI method


(CATI+CAWI+PAPI)


Work 7.7% 11.6% 9.8% 10.3% 9.9%

Buisiness trips 1.2% 2.1% 1.7% 2.4% 1.8%

Education 3.7% 5.1% 4.5% 3.9% 4.4%

Leisure 18.5% 16.1% 17.2% 15.8% 16.9%

Shopping 11.6% 9.5% 10.4% 9.9% 10.3%

Visitation 12.5% 9.9% 11.1% 11.8% 11.2%

Service 4.3% 4.8% 4.6% 4.6% 4.6%

Others 0.2% 0.5% 0.4% 0.8% 0.5%

Back home 40.3% 40.4% 40.4% 40.5% 40.4%

Trip purpose


CATI: Share of „work“ and „business“ is lower due to high share of retiree

CAWI: Share of „education“ is high due to high ratio of young persons

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Significant differences between CATI and CAWI methods

Younger people have strong preference to join CAWI survey

Elderly or retired people clearly favor telephone interview

Conclusions and Outlook

PAPI method

Works well and provides reliable results without unexpected non-response effects

CATI + CAWI method

Combination of CATI and CAWI method provides similar results to PAPI method

As a result, most key figures of household and person attributes as well as mobility behavior are affected for both CATI and CAWI method

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Conclusions and Outlook

CAWI method alone leads to massive overrepresentation of younger people CATI method alone leads to overrepresentation of elderly people

Combination of CAWI method with more approved methods (especially CATI) is recommended

But: Combination of different survey methods leads to higher costs and complexity of survey

KIT – University of the State of Baden-Wuerttemberg and

National Research Center of the Helmholtz Association www.kit.edu

INSTITUTE FOR TRANSPORT STUDIES

Answer Young People Just Like Old People? –

Impacts and Consequences of Different

Household Travel Survey Methods

Dr.-Ing. Martin Kagerbauer, Karlsruhe Institute of Technology (KIT), Institute for Transport Studies [email protected] (eMail) +49 (721) 608-47734 (phone)

Thank you for your attention !

answer young people just like old people? impacts and ...answer young people just like old people?...

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