Journal of Official Statistics, Vol.21, No.4, 2005. pp. 605615

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Adjustments for Missing Data in a Swedish Vehicle Speed Survey

In a Swedish vehicle speed survey for a multi-stage sample of road sites, data are collected by use of a measurement device installed on the road. Typically, some of the vehicles passing a chosen site will remain unobserved. Therefore, we suggest dividing the traffic into weighting classes. The main difficulty is to adjust the observed number of vehicles for missing data. Within class, one proposal is to add vehicles imputed by the device; another to use registration probability weighting. Models for the errors in the number of imputed vehicles, and in the estimated registration probabilities, enable theoretical evaluations of the proposals. From some empirical data, the models are evaluated.

Weighting classes, imputation, response probability, error model

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ISSN 0282-423X
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