Impact of Nonresponse and Weighting in a Swedish Survey

Download
Susanne Gustafsson

Results from travel surveys, together with traffic monitoring programs, serve as a basis for policy decisions and evaluations. Correct interpretation of the survey results is therefore of vital importance, and the impact of different sources of error needs to be investigated. This paper presents a study of nonresponse errors in a Swedish travel survey. Survey methodologists have addressed the problem of nonresponse for a long time, and several methods have been developed to reduce possible bias. Particularly common are different weighting methods based on auxiliary information. However, the performance of these techniques is based on how well the chosen auxiliary variables can explain the response behavior. The aims of the present study were to (a) investigate whether the mobility of nonrespondents differs from the mobility of respondents and (b) determine whether weighting reduces possible nonresponse bias. A weighting technique called calibration was used. The travel survey was based on a mail questionnaire, and the response rate was about 53%. Nonrespondents were contacted by telephone and asked a selected number of questions from the original questionnaire. Results show that mobility did differ between respondents and nonrespondents for some of the travel modes. The effect of calibration was generally small and inconsistent; the bias was reduced in some cases and increased in others. Nevertheless, calibration is recommended if procedures for calculating the weights are readily available.

MEET US


5-6
Dec

Vision Zero for Sustainable Road Safety in the Baltic Sea Region

The conference Vision Zero for Sustainable Road Safety in the Baltic Sea Region is held i Vilnius, Lithuania. VTI is part of the organisation committé and also one of the speakers.

LATEST NEWS


2018-10-18

ADAS&ME is tackling the interaction between people and technology

ADAS&ME is a major EU project focused on automation, the human condition and the human environment. The budget is EUR 9.6 million and VTI is the coordinator.


2018-10-05

Users contribute to the development of train simulators

Apart from advanced driving simulators, VTI has developed several variations of train simulators which are used for training, education and research. In recent years, interest has increased drastically among major actors in the railway sector, and VTI has...


2018-10-03

VR study to contribute to a better working environment for bus drivers

A study where bus drivers test autonomous driving in a VR environment may contribute to a better working environment with reduced stress on the driver and safer driving.


2018-10-02

Non-native plant species spread via transport systems

Researchers at VTI have compiled a report on non-native invasive plant species in Sweden and how they spread via transport systems.


2018-09-20

EU-project VIRTUAL: improving road safety with virtual crash tests

Crash tests are used to improve safety on roads. Therefore the EU now funds a research project to develop virtual methods of crash testing. VTI coordinates the project, called VIRTUAL. The project now invites experts interested in Human Body Modeling to join...


2018-08-28

EU project protects cyclists and pedestrians

According to the World Health Organisation, more than one quarter of road traffic fatalities in 2010 were pedestrians and cyclists. Every year, about 335,000 unprotected road users die because of traffic accidents, which shows the scale of the problem. The EU...