PSYCH 3980 EXAM 3- QUESTIONS AND
ANSWERS | 2026 UPDATE | 100% CORRECT
Threat to internal validity:
Researchers were interested in examining the effectiveness of a cognitive-
behavioral treatment on students' stress levels. The researchers made contact with
several university counseling centers and recruited participants with extremely
high stress levels. Any post-treatment improvement could have been due to the
treatment, but it could also have been due to what? - ANSWER-Regression to the
mean - it can occur when participants have been selected on the basis of extreme
scores, because extreme (low and high) scores in a distribution tend to move closer
to the mean (i.e., regress) in repeated testing. It is possible the student might have
gotten better without any treatment. A control group would be helpful in reducing
this.
Threat to internal validity:
Researchers are interested in examining how mindfulness influences motivation to
exercise. College students are randomly assigned either to the treatment condition
(e.g., weekly lectures plus journaling on mindfulness) or to the control condition
(e.g., no information or activities). Some students, who are assigned to the
treatment condition, begin feeling overwhelmed with the requirements of both
school and the study. Many of them stop going to the lectures and journaling, and
evenly drop out of the study. At the end of the study, researchers find those in the
treatment condition had significantly more motivation to exercise than those in the
control condition - ANSWER-Selection bias - because random assignment was not
used, the groups may not be equivalent at the beginning of the study. That is, there
may be differences between those who show up first versus those who show up
last.
Threat to internal validity:
A researcher uses the same set of problems to measure change over time in student
ability to solve mathematics word problems. The first administration is given at the
beginning of a unit of instruction; the second administration is given at the end of
the unit of instruction, three weeks later. Improvement scores res - ANSWER-
Maturation- students get used to the same set of problems
, Threat to internal validity:
Over a period of three years, a group of 20 teachers are observed closely by
external evaluators as they undergo a series of workshops aimed at improving their
quality of teaching. At the end, the evaluators observe the same 20 teachers,
systematically, as they teach. Their quality of teaching has improved according to
criteria for improvement (agreed-upon definitions and behavior). - ANSWER-
Instrumentation- the observers may have begun to drift away from their criteria.
*can argue maturation, regardless of the workshop, may have made improvements
anyway
Threat to internal validity:
A researcher decides to try a new mathematics curriculum in a nearby elementary
school and to compare student achievement in math with that of students in another
elementary school using the regular curriculum. The researcher is not aware,
however, that the students in the "new curriculum" school have computers to use in
their classrooms. - ANSWER-History- Computer usage in new curriculum schools
Threat to internal validity:
Concerned about pretest sensitization, a researcher constructs a test that is
extremely difficult, and that is not content valid, and administers it to both the
experimental and control groups. The posttest used to measure gains in
achievement is not as difficult, and the experimental group shows a slight larger
improvement over the control group - ANSWER-Instrumentation- varying levels
of difficulty in the pre test and post test
Threat to internal validity:
Researchers want to evaluate a pre-school readiness program for 3- to 4-year-olds.
To determine the effectiveness of the program, the researchers randomly assign
their children either to participate in the readiness program or the daycare program.
During the course of the study several parents notice that their children are
performing poorly in the readiness program. These parents decide to take their
children out of the program. - ANSWER-Experimental Mortality (attrition)- the
low scorers have dropped out. The loss of low-end scorers may artificially raise the
overall mean for those in the readiness program creating the impression of a
program effect when there is none.
ANSWERS | 2026 UPDATE | 100% CORRECT
Threat to internal validity:
Researchers were interested in examining the effectiveness of a cognitive-
behavioral treatment on students' stress levels. The researchers made contact with
several university counseling centers and recruited participants with extremely
high stress levels. Any post-treatment improvement could have been due to the
treatment, but it could also have been due to what? - ANSWER-Regression to the
mean - it can occur when participants have been selected on the basis of extreme
scores, because extreme (low and high) scores in a distribution tend to move closer
to the mean (i.e., regress) in repeated testing. It is possible the student might have
gotten better without any treatment. A control group would be helpful in reducing
this.
Threat to internal validity:
Researchers are interested in examining how mindfulness influences motivation to
exercise. College students are randomly assigned either to the treatment condition
(e.g., weekly lectures plus journaling on mindfulness) or to the control condition
(e.g., no information or activities). Some students, who are assigned to the
treatment condition, begin feeling overwhelmed with the requirements of both
school and the study. Many of them stop going to the lectures and journaling, and
evenly drop out of the study. At the end of the study, researchers find those in the
treatment condition had significantly more motivation to exercise than those in the
control condition - ANSWER-Selection bias - because random assignment was not
used, the groups may not be equivalent at the beginning of the study. That is, there
may be differences between those who show up first versus those who show up
last.
Threat to internal validity:
A researcher uses the same set of problems to measure change over time in student
ability to solve mathematics word problems. The first administration is given at the
beginning of a unit of instruction; the second administration is given at the end of
the unit of instruction, three weeks later. Improvement scores res - ANSWER-
Maturation- students get used to the same set of problems
, Threat to internal validity:
Over a period of three years, a group of 20 teachers are observed closely by
external evaluators as they undergo a series of workshops aimed at improving their
quality of teaching. At the end, the evaluators observe the same 20 teachers,
systematically, as they teach. Their quality of teaching has improved according to
criteria for improvement (agreed-upon definitions and behavior). - ANSWER-
Instrumentation- the observers may have begun to drift away from their criteria.
*can argue maturation, regardless of the workshop, may have made improvements
anyway
Threat to internal validity:
A researcher decides to try a new mathematics curriculum in a nearby elementary
school and to compare student achievement in math with that of students in another
elementary school using the regular curriculum. The researcher is not aware,
however, that the students in the "new curriculum" school have computers to use in
their classrooms. - ANSWER-History- Computer usage in new curriculum schools
Threat to internal validity:
Concerned about pretest sensitization, a researcher constructs a test that is
extremely difficult, and that is not content valid, and administers it to both the
experimental and control groups. The posttest used to measure gains in
achievement is not as difficult, and the experimental group shows a slight larger
improvement over the control group - ANSWER-Instrumentation- varying levels
of difficulty in the pre test and post test
Threat to internal validity:
Researchers want to evaluate a pre-school readiness program for 3- to 4-year-olds.
To determine the effectiveness of the program, the researchers randomly assign
their children either to participate in the readiness program or the daycare program.
During the course of the study several parents notice that their children are
performing poorly in the readiness program. These parents decide to take their
children out of the program. - ANSWER-Experimental Mortality (attrition)- the
low scorers have dropped out. The loss of low-end scorers may artificially raise the
overall mean for those in the readiness program creating the impression of a
program effect when there is none.
