For each of the following state whether the data are observa

For each of the following state whether the data are observational or experimental

(a)

Data on earnings for individuals some of whom chose to participate in a training program and

some who did not.

(b)

Data on earnings for individuals some of whom were randomly assigned to a training program

and some who were not.

(c)

Data on school outcomes for charter schools and for traditional schools.

Solution

In case of an observational study, data is passively recorded (observed) from each unit.

In case of experimental data, some changes in characteristics of units is made before collecting the data.