You want to conduct a study involving the use of technology by 20, 40, 60, and 80 -year olds

Question

However, a colleague tells you that your study will fail because your participants will
naturally vary on important variables such as education.

Your colleague adds that matching
your participants on demographic variables will solve one problem, but create another. That
is, your age groups are equated on these variables, but in doing so, you have compromised
external validity.  Describe how you would respond to your colleague's critique.
What will be an ideal response?

Answer 1

Because the participants in the age groups may be very different in terms of key
variables, such as education and health, one should incorporate certain controls. For
example, the participants could be matched on verbal intelligence and health. To
determine if this control has influenced external validity, one could contrast the verbal
intellect and health of the participants to the broader population in the community, or in
the case of verbal intellect, contrast the scores of the participants within age groups to
the national statistical average for people of a particular age group.