Ch. 10 Experimental Designs
Subgroups:
1. Between subject design
a. Subjects assigned to independent groups using randomization
2. Randomized block design
a. Subjects classified according to attribute variable and then randomized to
treatment groups
3. Within-subject design or repeated measures design
a. one group of subjects is tested under all conditions and each subject acts as his
own control
b. considered series of trails each with a single subject
4. Single-factor or one-way design or multi-factorial
a. Experimental designs can also be described according to the number of
independent variables or factors
5.Pretest-posttest control group design
6. Mixed design
a. Study incorporates two independent variables, one repeated across all subjects and the
other randomized to independent groups
Ch. 11 Quasi-experimental
 Will LACK random assignment OR comparison groups OR both
 Used as reasonable alternative to randomized trial design
Subgroups:
1. One group pretest-posttest design
a. One set of repeated measures taken before and after treatment on one group of
subjects
2. Time series design
a. Multiple measurements before and after treatment used to study community
interventions and policy changes
3. Nonequivalent pretest-posttest control group
a. Subjects are self-selected due to research situations in social, clinical, and
behavioral sciences
b. Subjects not assigned to groups randomly- one treatment group, one control group
4. Nonequivalent posttest-only control group design
a. Includes any number of treatment levels, with or without control group
b. Uses existing groups who have and have not received treatment
Ch. 12 Single-Subject Designs
 Must have a collection of repeated measurements of a behavioral response over time
 Must have 2 testing periods or phases: baseline and intervention
Subgroups:
1. Withdrawal design
a. Includes a second baseline and maybe a second intervention
2. Multiple baseline designs
3. Alternating treatment design
4. Multiple treatment design
Chapter Outline 13
 Observational-study that does not involve an intervention or a manipulation of
an independent variable.
 Exoploratory research-research that has as its purpose the exploration of data to
determine relationships among variables
RETROSPECTIVE AND PROSPECTIVE RESEARCH:

Prospective research- study designed to collect data following development
of the research question

Retrospective research- study that analyzes observations that were
collected in the past.
LONGITUDINAL AND CROSS-SECTIONAL RESEARCH:

Longitudinal Research- study designed to collect data over time, usually the
purpose of describing developmental changes in a particular group.

Cross-Sectional Research- study based on observations of a different age or
developmental groups at one point in time, providing the basis for inferring
trends over time.
CORRELATION AND PREDICTION:

Correlation- measure of the degree of association between variables.

Correlational research- descriptive research approach that explores the
relationship among variables without active manipulation of the variables
by the researcher.

Predictive Correlational Study- study designed to predict a behavior or
response based on the observed relationship between the behavior and
other variables

Regression Analysis- a statistical procedure for examining the predictive
relationship between a dependent (criterion) variable and an independent
(predictor) variable
CASE-CONTROL STUDIES:
o Selection of Cases and Controls
 Selection of Cases:
a. Population based study- study that obtains a sample of cases
from the general population of those with the disorder
b. Hospital based study- study in which cases are obtained from
patients in a medical instituiton.

Selection of Controls- controls can be selected from several
sources. They are often recruited from the same hospital or
instiutution as the cases, from those admitted for conditions
other than the disease of interest.
COHORT STUDIES:

Cohort study- an observational study design in which a specific group is followed
over time. Subjects are classified according to whether they do or do not have a
particular risk factor or exposure and followed to determine disease outcomes.

Prospective- study designed to collect data following development of the
research question

Retrospective- study that analyzes observations that were collected in the past.
EVALUATING CAUSALITY IN OBSERVATIONAL STUDIES:

Observational study-study that does not involve an intervention or manipulation
of an independent variable.
Dose- response relationship- provides evidence for causality. This means that
the severity of the disease can be associated with varying levels of exposures.
METHODOLOGICAL RESEARCH: RELIABILITY AND VALIDITY :
Methodological Research- research designed to develop or refine procedures or
instruments for measuring variables, generally focusing on reliability and validity.
o Reliability Questions
 Testing the Rater
o Validity Questions
 HISTORICAL RESEARCH
Historical Research- research that seeks to examine relationships and facts based
on documentation from the past.
Reliability and Validity:
a. External criticism- establishing the authenticity of data.
b. Internal criticism- questions the truth or worth of the material’s content within
the context of the research question.
Secondary Analysis- an approach to research involving the use of data that were
collected for another purpose, usually for the purpose of testing new hypotheses.