HDF 202 URI Quiz 5

Pre-test only

The advantage of using a pretest is that it permits researchers to determine how much each group has gained, not just whether they are different at the end of the experiment.

null hypothesis

The hypothesis used for statistical purposes, that the variables under investigation are not related in the population, that any observed effect based on sample results is due to random error.

Subject mortality (attrition)

The loss of subjects who decide to leave an experiment.

Maturation

The possibility that any naturally occurring change within the individual is responsible for the results.

Type I error

The rejection of a true null hypothesis (false positive)

Pre-experimental designs

Have limited value for investigating cause and effect relationship because of their poor internal validity.

One Shot Case Study

One group is given a treatment followed by the observation. (not a good design)

Equivalent Time Sample (ABAB)

-A quasi experimental design that has only one group and the participants serve as both the control and experimental group. -Treatment conditions are alternative and the participants receive the treatment at X1 and not X0. -This designs advantage is that we know the treatment and experimental groups are identical. The disadvantage is the possibility of multiple treatment interference.

External Validity

-Can the findings be generalized to other situations outside the experimental situation? -Established during sampling procedure -Increase by bigger sample size, and conducting study under different settings and times.

Internal Validity

-Refers to how well the experiment is done -Manipulating the IV -Holding conditions constant -Randomly assigning subjects to treatment conditions.

Static group comparison design

-These are two groups, but the participants are not assigned to groups at random. -This is known as a natural or intact group design.

Reactivity

A problem of measurement in which the measure changes the behavior being observed.

Non-equivalent control group design

A quasi-experimental design in which nonequivalent groups of subjects participate in the different experimental groups, and there is no pretest.

One group Pre-Test Post-Test

A quasi-experimental design in which the effect of an independent variable is inferred from the pretest-posttest difference in a single group.

Testing

A threat to internal validity in which taking a pretest changes behavior without any effect on the independent variable.

Pretest Posttest design

A true experimental design in which the dependent variable is measured both before (pretest) and after (posttest) manipulation of the independent variable.

Quasi-Experimental Design

A type of design that approximates the control features of true experiments to infer that given treatment did have its intended effect.

Regression

Because some component of a test score is due to error, there is a tendency for subjects with either extremely high or extremely low scores on an initial test to perform closer to the mean of the group on second test.

Instrumentation

Changes over time in the instruments used to measure behavior.

Selection

Differences that exist between different groups of subjects from the outset of the experiment.

Solomon 4 group design

Experimental design in which the experimental and control groups are studied with and without a pretest.

Control Group Designs

Random assignment to subjects and control conditions. Allows us to look at cause and effect.

what does it mean when the sample data falls in the critical region?

Reject the null hypothesis

Contamination effects

Results when there is communication between groups of participants.

Type II error

Retaining a false null hypothesis (false negative)

Threats to validity of a study

history, maturation, testing, instrumentation, regression, selection, subject mortality, contamination effects, expectancy effects, reactivity.

History

refers to any outside event that is not part of the manipulation that could be responsible for the results.