Question

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.

Answer 1

Observational data are those where the person collecting data have no control and these data can't be manipulated Experimental data are where the person collecting data can manipulate by choosing where to collect data and who will be participating etc.

a) This data is experimental. As the collector can separate the two groups and evaluate them. The collector has ability to control and manipulate the outcome.

b) This data is experimental as the collector has the power to choose the individuals who can be selected to collect data.

c) This data is observational as the collector have no control over the data. If the collector has the authority or discretion to choose which schools will represent the charter school and which will represent tradition than matter was different.