Är trängselskatt ett hot mot detaljhandeln

5.1 CONCLUDING REMARKS
Could the survey have been carried out better with a different approach? The answer to this is
partly yes. The descriptive and econometric analysis of development of retail sales is based on
direct information from participating department stores, shopping centres and free-standing
shops. The information collected about development within the congestion charge zone is
almost of total coverage. There are a few shopping centres that did not participate in the
survey but their market share is limited why their development would not have affected the
final outcome.
Information collected outside the charge zone included a limited number of larger shopping
centres in the Stockholm area. Possibly, a larger number of respondents, more shopping
centres - even smaller centres and in a wider geographic area - could have affected the
analysis. In this study, time restrictions in connection with the Stockholm trial made it
impossible to contact respondents to a larger extent. The strength of the method used is that
the information – turnover rates for each line of retail business – collected at the time is
secured by being obtained directly from real estate owners or proprietors. In connection with
the study HUI has had the possibility to secure the accuracy of the information by
interviewing the information provider.
Could the survey have shown a different result if HUI had used alternative material? The
answer to this question must be no. Alternative material in the form of tax statistics from the
government authority Statistics Sweden was also used. These statistics offer a number of
possibilities but is by HUI judged also to suffer from such large shortcomings that it cannot be
used without an extensive work to secure the quality of the information. The strengths that
can be noticed is that the statistics enable examination of lines of retail business at a detailed
geographic level. HUI’s experience from the congestion charge programme and several other
studies is that turnover and growth rate figures are often unsure. Some of the sources of error
are incorrect classification of line of business, delay of reported information, sector
convergence and inexact tax statements. That is why results based on official statistics may be
insecure.
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