How do you read a many to one merge row?

A many to one merge row shows two or more NACE Rev. 2 classes merged into one class in NACE Rev. 2.1. The Eurostat manual states the definition, and gives the count as 25 NACE Rev. 2 classes merged into one class in the new version, using the notation n to 1. A merge row combines old scopes into a new scope. A merge row supports adding old totals together for a comparison, because the new total covers the combined old scope. It does not, on its own, preserve the old detail, and it does not decide an entry.

What are the verified merge examples?

Two verified merges from the manual changelog are used as worked examples. In agriculture, classes 01.63 for post harvest crop activities, and 01.64 for seed processing for propagation, were merged into one new class 01.63 for post harvest crop activities and seed processing for propagation. The manual states the merger in the passage on Section A. In wholesale trade, classes 46.51 for wholesale of computers, computer peripheral equipment and software, and 46.52 for wholesale of electronic and telecommunications equipment and parts, were merged into class 46.50 for wholesale of information and communication equipment. The manual states that merger in the passage on Section G.

The two examples show different code patterns for a merger. In the agriculture example, the new class reuses one of the old codes, 01.63, with a combined heading. In the wholesale example, the new class uses a new code, 46.50, with a combined heading. A reader must therefore not assume that a reused code means an unchanged scope, or that a new code means a new scope with no old content. The code pattern is a coding decision. The scope is stated in the note for the new class, and the correspondence table shows the type and the old classes combined. The note and the table together, not the code alone, state the merger.

Merge example in the manual	Old classes	New class
Agriculture, Section A	01.63 and 01.64	01.63 post harvest crop activities and seed processing for propagation
Wholesale, Section G	46.51 and 46.52	46.50 wholesale of information and communication equipment

How is a merge row used for a comparison?

A merge row is used for a comparison by adding the old totals. The total for the new class, for a reference period under the new version, can be compared with the sum of the totals for the old classes, for a reference period under the old version, provided that the population and the domain are the same apart from the classification, and that no other break affects the comparison. The table supports the addition, because it states that the joint scope of the old classes is the scope of the new class. The comparison is therefore a comparison of combined scopes, not a comparison of individual old classes with the new class. A comparison of one old class alone with the new class will overstate the growth, because the new class also covers the other old class.

A merge row does not support recovering the old detail from the new total. The new total is a single figure for the combined scope. The division of that total between the old classes cannot be derived from the table, and it cannot be derived from the new note, because the new note states the combined scope, not the old division. Where the old detail is needed for a series, a backcast series or a double reported series must be used, where the old and new versions are tabulated in parallel for the same reference period. The table is the framework for that parallel tabulation, not a substitute for it.

What must be checked in the note for a merged class?

The heading for the merged class must also be read with care. In the agriculture example, the heading combines the two old headings with the word and. In the wholesale example, the heading uses a broader term, information and communication equipment, that covers both old headings. A broader heading does not necessarily mean a broader scope than the combined old scopes. The scope is the joint scope of the old classes, as stated in the correspondence definition, subject to the note. The heading is a label for that joint scope, and the note is the definition. A reader who treats a broader heading as if it covered activities beyond the old joint scope, without checking the note, will overread the merger.

What does a merge row not guarantee?

A merge row does not guarantee that every activity in the old classes is treated in the same way in the new class for every statistical purpose, and it does not guarantee an entry for a unit. It guarantees a category relationship: the joint scope of the old classes is the scope of the new class, as stated in the manual definition. The application of that relationship to a unit, for its principal activity, is made by the institute or register that holds the record, using the notes and the classification rules. A reader who follows a merge row to a new code for a specific business has used a category relationship as if it were an assignment, and has skipped the assignment step.

Trace the merger in the manual changelog, read the new class note for the combined scope, and confirm any entry with the national statistical institute or the business register that holds the record.