I wonder if you could help me with answers,

1. If we measured each of the following variables for every person in this class, which variable would have the most measurement error variability?

1. Students' report of their parents' annual income.

2. Parents' annual income recorded from official tax forms.

2. If we measured each of the following variables for every person in this class, which variable would have the least individual differences variability?

1. Number of siblings a person has.

2. Number of fingers a person has.