Statistical processing

Source data

Data comes from an internal statistical register and an external administrative register. The population, including the persons' weight status, originates from the National Child Health Register administered by the Danish Health Data Authority, while information on sex, age and geography comes from the population statistics.

Frequency of data collection

Data are collected yearly.

Data collection

Data are collected directly from internal administrative registers.

Data validation

During the data processing, the population's height and weight measurements are manually validated and troubleshot. Among the 6-7-year-old children, it has been chosen to only include observations where the height is 80-179 cm and the weight is 10 kg or more. Likewise, among the 14-15-year-olds, it has been chosen to only include observations where the height is ≥80 cm and the weight is ≥20 kg.

Data compilation

The population, including the persons' weight status, sex, and age, is identified from the National Child Health Register and linked with the population statistics' information on the municipality of residence at the time of measurement using the population's deidentified personal identification numbers.

The population only includes children and young people who have had their height and weight measured at school in connection with the statutory introductory schooling and school-leaving examinations since 2012, as it did not become mandatory for the municipalities to report to the National Child Health Register until the end of 2011. Since the introductory schooling examination must take place in the 0th or 1st grade, while the school-leaving examination must take place in the 8th or 9th grade, the population is further limited to children aged 6-7 and young people aged 14-15. For children and young people with several measurements of height and weight, the most recently recorded measurement is used.

Data are grouped in relation to sex, age and geography (municipality group and municipality, cf. the municipality groups classification).

Overweight among children is calculated as the proportion of children within a given group whose BMI is classified as overweight or obese.

Weights are not used.

Adjustment

No adjustments are made beyond what is already described under Data validation and Data compilation.