Statistical processing

Source data

The source of information is from a sample of road goods vehicles drawn from the stock of vehicle registered in the Danish digital motor vehicle register. A stratified sample is drawn from all lorries and road tractors with maximum permissible laden weight above 6 tonnes. About 2,000 vehicles is selected each quarter. The sample is around 4.5 percent of the stock of relevant road goods vehicles (lorries and trucks). For each vehicle the data provider must report transport during a single week (Sunday to Saturday). The true sample size is thus 0.35 percent of possible vehicle weeks.

The vehicles are divided into 35 groups according to type of transport, type of vehicle (lorries and trucks), total laden weight, available hitch and average annual kilometers driven. The sample is distributed between the groups to optimize the sample size given the requirements of statistical precision on transport performance measures.

The stratification is determined by the following characteristics (note that not all combinations exist and therefore there are only 35 and not 42 strata):

First digit

1 = 'Solo lorries (mostly)'

2 = 'Lorries with hook, 15-18 ton'

3 = 'Lorries with hook, 18-24 ton'

4 = 'Lorries with hook, 24 ton +'

5 = 'Road tractors, -18 ton'

6 = 'Road tractors, 18-24 ton'

7 = 'Road tractors, 24 ton +'

Second digit

1 = 'For hire or reward'

2 = 'Own account'

• Third digit *

1 = "Driven less than median for segment"

2 = "Driven more than median for segment"

3 = "New car (no road worthiness tests)"

The selected vehicles are then distributed evenly over the weeks of the quarter.

Data are collected through web forms via the common public data collection platform, Virk and a mobile app (vejgodsstatistikken) available on iOS and Android platforms.

Frequency of data collection

Data are collected weekly and publish quarterly.

Data collection

Data are collected through web forms via the common public data collection platform, Virk and an mobile app working on iOS and Android devices. An information page for data providers are available in Danish.

Data validation

The collected data are validated with respect to the correctness of reported data and data consistency.

Consistency checks ensure coherence between the different data elements, e.g. if the weight of the goods exceeds the maximum laden weight of the vehicle. The checks involve coherency in total laden weight, laden weight, number of axles, kilometres driven and likewise.

Probability checks focuses on journeys with very small or large values in kilometres or goods weight and the type of goods.

Data compilation

Data is reported by enterprises with transport by own account or for hire or reward.

The questionnaires are sent out one week at a time to be at the data provider a week before the reporting week begins. The responses are categorised as

1. Active during the week
2. Vehicle sold/deregistered
3. The vehicle is not used to carry goods
4. The vehicle was not active

In case of the last two categories a reason must be specified further. Only sold/deregistered vehicles and non-response is not included in the estimation and thus in the statistics. Sold/deregistered vehicles are about 8 percent of respondents while non-response typically is about 1 percent in first versions and below 0.1 percent in final figures.

All other vehicles are included in the processing. Of these around 60 percent are with information on journeys. The remaining vehicles are reported as inactive in the reference week because of lack of orders, holiday closure or not used for goods transport. The vehicles not used for goods transport could be special vehicles (mobile libraries, fire truck, tow truck, driving school vehicles, snow plows, sweepers) or vehicles used for use off public accessible roads.

The statistics are enumerated to a totals by a weight expressed as the number of weeks in the quarter (typically 13) times the number of vehicles in the population within the stratum (N) divided by the number of vehicles in the sample (excluding non-response and sold/deregistered vehicles) within stratum (n), i.e. the weight is 13*N/n.

Adjustment

The series are seasonally adjusted using the tool J-Demetra+.