7 Identifiers
The harmonized dataset preserves the original individual study identifiers while also providing harmonized identifiers and project metadata to support data management, reproducibility, and traceability.
The pooled dataset includes the following identifiers and metadata:
| File | Identifiers and metadata |
|---|---|
| Main pooled data file | country, year, original school_id, original student_id, harm_student_id, country_iso, project_code, study_type, study_design, round, school_code (harmonized school id), pupil_code |
Table 9: Identifiers in the pooled dataset
The interactive browser provides more context on the project related variables.
7.1 Original identifiers (school_id, student_id)
school_id and student_id are retained in string format. See Demographics and pupil context for identifier scope and linkage limitations.
Although some projects followed the same schools over multiple rounds, school_id and student_id alone do not constitute pupil-level longitudinal identifiers. Whether longitudinal linkage at the pupil level is available depends on the release; consult the Release Notes for the current release for details.
Use the interactive browser to trace back to the original DataLumos files and their codebooks.
7.2 Harmonized student ID (harm_student_id)
The pooled dataset includes harmonized identifiers to facilitate data management within the pooled database. The variable harm_student_id provides a unique, fixed-width identifier for each pupil record. It encodes the project structure, the round of data collection, school, and pupil codes, creating a stable key for uniquely identifying records within the harmonized dataset.
The structure of harm_student_id is described in the table below:
| Position | Component | Width | Meaning |
|---|---|---|---|
| 1–2 | country_iso |
2 | ISO-3166 alpha-2 (e.g. KE, RW) |
| 3–5 | project_code |
3 | Zero-padded project code within country |
| 6 | round |
1 | Collection round within project (1–9) |
| 7–9 | school_code |
3 | Harmonized school rank within country+project+round |
| 10–12 | pupil_code |
3 | Harmonized pupil rank within school |
Table 10: Harmonized identifier components
Assignment logic (interpretive): school_code and pupil_code are derived from original school_id and student_id where present; missing pupil IDs receive sequential placeholders within the school. Codes are assigned within each country_iso + project_code + round combination — the same original school in two rounds receives a different harm_student_id because the round digit changes. By construction, harm_student_id is unique within each country_iso + project_code + round.