The language to which the child was exposed during early development and continues to use this language in the home or in the community. If a child acquires English subsequent to early development, then English is not their first language no matter how proficient in it they become.
2005 - 06
Data is given a sensitivity scale. Items are rated from A to E with A being highly sensitive and E being low.
Data is scored on identifiability scale from 1 to 5, the lower the number the higher the identifiability.