A data.table with 15 rows and 6 variables:
- country
Factor with levels: "A", "B".
- year
Numeric, with values: 2010-2017.
- variable1
Numeric.
- variable2
Numeric.
- variable3
Numeric.
- variable4
Numeric.
Source
Variation of survey_data with non-unique ids and a m:1 relationship between ids and values.