1. Andrea M. Landis, PhD, RN UW LEAH
Research Designs
Andrea M. Landis, PhD, RN
UW LEAH

2. Learning Objectives Discuss concepts important to research design
Identify threats of internal validity
Review different types of non-experimental, experimental, and quasi-experimental research designs

3. Research Design: Definition and Characteristics
The vehicle for hypothesis testing or answering research questions
A blueprint for conducting a study
Maximizes control over factors that could negatively effect the validity of study findings
Guides the researcher in planning and conducting a study
Links the steps of the research process in the study

4. Concepts Important to Research Design
Causality
Cause is not directly observable but must be observed
The cause is necessary for the effect to occur
Multicausality – recognition that a number of interrelating variables can be involved in causing a particular effect
Probability – Addresses the likelihood that something will happen in a given situation
Bias
To slant away from the truth or the expected
Failing to consider or include both sides of the question or hypothesis
Control – A check or comparison. Methods to keep the study conditions constant during the study

5. Forms of Control
Manipulation – Researcher exercises by specifying the IV
Elimination or Inclusion – Holding certain aspects of intervening and extraneous variables constant
Statistical – Controlling extraneous variables by including them in the statistical analysis
Randomization – Distribution of effects of extraneous variables via change with assignment of subjects to groups based on probability
What is the difference between random sampling and random assignment?

6. Concepts Important to Research Design
Study Validity – truth or accuracy of the study findings.
Internal Validity – extent to which the effects detected in the study are a true reflection of reality.
External Validity – extent to which the findings of the study can be generalized to the general population

7. Threats of Internal Validity
History: due to intervening events between pre- and post- test
Maturation: produced by changes in members in one group which occurred at a different rate than in the comparison group between data points
Testing: created by repeated measurement
Instrumentation: produced by a change in the measuring instrument between the pre- and post-test
Selection: differences between the kinds of people in an experimental group in comparison to the other(s). Due to lack of random placement of subjects into two groups.

8. Threats of Internal Validity
Mortality: due to differences in those who dropped out of a particular treatment group versus the comparison group(s)
Ambiguity About the Direction of Causal Influence: occurs when cause and effect variables are measured at the same time (e.g., correlational studies)
Diffusion or Imitation or Treatments: spurious communication of the treatment to the control group(s)
Compensatory Equalization of Treatments: when the control group receives the treatment inadvertently because it is seen by administrators or health care providers to be best for patients
Reactive Effect: produced by a data collector or a subject’s response to being in a study which improves subject performance or behavior

9. Types of Research Designs
Non-experimental – both randomization and manipulation absent
Experimental – both randomization and manipulation present
True or classic experiment
Quasi-experimental – manipulation present, but not randomization
One-group (pretest – posttest) design

10. Major Categories of Non-experimental Designs
Descriptive
Designed to document conditions, attitudes, or characteristics of individuals or groups
Exploratory
Focuses on the relationships among these factors
Predictive
Aimed at the development of systems to predict criteria of interest by utilizing information from one or more predictors
Explanatory
Aimed at testing of hypotheses formulated to explain phenomena of interest. Involves theoretical model testing.

11. Methods of Non-Experimental Research
Retrospective (ex post facto)
Involves examining data that have been collected in the past, often obtained from medical records or survey
Prospective
Variables are measured through direct recording in the present
Longitudinal
Follows a cohort of subjects over time, performing repeated measurements at prescribed intervals
Cross-sectional
Researcher studies a stratified group of subjects at one point in time and draws conclusions about development within a population by comparing the characteristics of those strata.

12. Perspectives in Qualitative Research Designs
Phenomenology
Seeks to draw meaning of experiences through narrative subject materials. Words like “lived experience” often describe phenomenological studies.
Ethnography
Study of the social milieu of a specific cultural group or people. Researcher often immersed in subject’s way of life.
Grounded Theory
Researcher uses data to develop a theory that will explain what is observed. Researcher collects, codes, and analyzes data simultaneously.

13. Epidemiological Research
Concerned with the study of the distribution of disease, injury, or dysfunction in human populations
Observational Epidemiologic Studies
Gather measures about disease frequency: prevalence (existing cases), incidence (new cases)
Analytic Epidemiologic – Used when enough is known about a condition to allow testing of hypotheses about the association of specific risk factors (exposures) and outcomes
Case-control studies – groups of individuals are selected on the basis of whether they have the disorder under study
Cohort studies – group of individuals followed over time to determine if they will develop a disorder

14. Nontraditional Designs: Examples
Methodological Designs
Used to develop research approaches or the R/V of instruments to measure constructs used as variables in research
Secondary Analysis
Studying data previously collected in another study
Meta-Analysis Designs
Involves merging findings from many studies that have examined the same phenomenon

15. Levels of Evidence