Identify the threat to external validity in the following
examples:
a. A teacher read research reporting great results from
using a particular remedial reading program. She tried the program in her
classroom but did not get the same results.
b. A teacher read about a new method of instruction that was
very successful with regular classes. The method did not work when she tried it
with her special education students.
c. A research journal reported that a new antismoking fi lm
had brought about a signifi cant change in students’ attitudes. After viewing
the fi lm, students expressed many more negative attitudes toward smoking than
they had on a prefi lm measure. A teacher decided to use the fi lm with his
middle school students but did not want to take time to administer the
“pretest.” He administered an attitude scale following the fi lm but did not fi
nd marked negative attitudes toward smoking.
Leave a Reply