Political pollsters now make sure to conduct a percentage of their telephone interviews by calling mobile phones. this policy best addresses which potential source of bias?
lack of access
voluntary response
wording bias
nonresponse

answer:

d. because dr. laguardia selected a widely used measure, his study generalizes to has strong external validity. external validity has limited external validity. other applications of this measure.

the widely used measure that he applied to his experiment was the benton facial recognition test. it employed on to football players and as result, only players who suffered brain concussions did not pas this test. and although it has an external validity, it is limited because it isn't general to apply to other population.

you should try adrenaline. it kicks in in situations like this.