Chapter 18

The one characteristic of true experimental designs that preexperimental and quasi-experimental designs do not have is

random assignment to groups

A researcher finds that the control group performs above its usual performance when compared with the experimental group. This effect is named the

Avis effect

A study is designed to determine whether the addition of programmed instruction will produce greater achievement scores than the traditional lecture-discussion method. Participants are randomly assigned to two instructional groups. Both groups are tested at the end of the experimental period. What statistical test is indicated?

t test

Sometimes it is not possible to actually administer the treatment (e.g., when comparing children who had been in Head Start vs. children who had not). However, the researcher is trying to imply causation. This type of design (sometimes called causal comparative) is referred to as

an ex post facto design

In a research study in which the treatment involved quite intense physical training, 40% of the participants in the treatment group dropped out as compared with 5% of the control group. This threat to internal validity is called

experimental mortality

Multiple-treatment interference and the interaction of selection bias and experimental treatment are threats to

external validity

A pretest of knowledge about microcomputers is given to a group of students 5 minutes prior to a film on the subject. A posttest given 10 minutes after the film shows a 10-point gain from the pretest. The researcher concludes that the film produced the gain. Which of the following is likely the threat to internal validity?

testing

It is reasonable to expect volunteer participants to be similar in nature to

other volunteers from similar populations

The internal validity of an experimental design is concerned with what question?

Did the independent variable really produce a change in the dependent variable?

Individuals performing well merely because they are being observed (and not necessarily because of any effect of treatment) are considered to be under the influence of the

Hawthorne effect

A baseline in single subject research

establishes initial rates of behavior before an intervention

Just before the posttest, students in the control group were shown a film in another class that related directly to the subject matter being studied in the treatment group. This represents what kind of threat to internal validity?

history

The only true experimental design that can specifically evaluate the reactive or interactive effects of testing is the _______ design.

Solomon four-group