| Value |
Category |
| 1 |
Very easy |
| 2 |
Easy |
| 3 |
Uncertain |
| 4 |
Difficult |
| 5 |
Very difficult |
| 9 |
|
| 13 |
|
| 99 |
|
| 0 |
NR |
| Sysmiss |
|
Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.