2  Identification

2.1 p_id

p_id is the identification number that remains the same for each pupil throughout the entire testing period. It was newly generated each year by teachers at the schools and is based on a combination of the pupil#s first name, last name, date of birth, and an individual school-specific seed. Since the seed is only known to the respective school, the ID is pseudonymized.

var_name p_id
var_stat_dyn static
var_content_group id
var_info_type id
item_level_data is_no_scale
analysis_set_core TRUE
analysis_set_extended TRUE

The id is constructed as follows:

The first two digits represent a country code: “00” = “UK” and “01” = “DE”. The third and fourth digits indicate the school ID. The last two digits are check digits, meaning they are calculated as the checksum of the preceding numbers. In general, the IDs consist of 14 digits. Up to test wave 4, 10-digit IDs were partly used in the UK. If pupils did not continue participating in the testing after that point, the 10-digit ID remained unchanged.