Presentation on theme: "Andrea M. Landis, PhD, RN UW LEAH"— Presentation transcript:
1Andrea M. Landis, PhD, RN UW LEAH Research DesignsAndrea M. Landis, PhD, RNUW LEAH
2Learning Objectives Discuss concepts important to research design Identify threats of internal validityReview different types of non-experimental, experimental, and quasi-experimental research designs
3Research Design: Definition and Characteristics The vehicle for hypothesis testing or answering research questionsA blueprint for conducting a studyMaximizes control over factors that could negatively effect the validity of study findingsGuides the researcher in planning and conducting a studyLinks the steps of the research process in the study
4Concepts Important to Research Design CausalityCause is not directly observable but must be observedThe cause is necessary for the effect to occurMulticausality – recognition that a number of interrelating variables can be involved in causing a particular effectProbability – Addresses the likelihood that something will happen in a given situationBiasTo slant away from the truth or the expectedFailing to consider or include both sides of the question or hypothesisControl – A check or comparison. Methods to keep the study conditions constant during the study
5Forms of ControlManipulation – Researcher exercises by specifying the IVElimination or Inclusion – Holding certain aspects of intervening and extraneous variables constantStatistical – Controlling extraneous variables by including them in the statistical analysisRandomization – Distribution of effects of extraneous variables via change with assignment of subjects to groups based on probabilityWhat is the difference between random sampling and random assignment?
6Concepts 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
7Threats of Internal Validity History: due to intervening events between pre- and post- testMaturation: produced by changes in members in one group which occurred at a different rate than in the comparison group between data pointsTesting: created by repeated measurementInstrumentation: produced by a change in the measuring instrument between the pre- and post-testSelection: 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.
8Threats 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 patientsReactive Effect: produced by a data collector or a subject’s response to being in a study which improves subject performance or behavior
9Types of Research Designs Non-experimental – both randomization and manipulation absentExperimental – both randomization and manipulation presentTrue or classic experimentQuasi-experimental – manipulation present, but not randomizationOne-group (pretest – posttest) design
10Major Categories of Non-experimental Designs DescriptiveDesigned to document conditions, attitudes, or characteristics of individuals or groupsExploratoryFocuses on the relationships among these factorsPredictiveAimed at the development of systems to predict criteria of interest by utilizing information from one or more predictorsExplanatoryAimed at testing of hypotheses formulated to explain phenomena of interest. Involves theoretical model testing.
11Methods of Non-Experimental Research Retrospective (ex post facto)Involves examining data that have been collected in the past, often obtained from medical records or surveyProspectiveVariables are measured through direct recording in the presentLongitudinalFollows a cohort of subjects over time, performing repeated measurements at prescribed intervalsCross-sectionalResearcher 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.
12Perspectives in Qualitative Research Designs PhenomenologySeeks to draw meaning of experiences through narrative subject materials. Words like “lived experience” often describe phenomenological studies.EthnographyStudy of the social milieu of a specific cultural group or people. Researcher often immersed in subject’s way of life.Grounded TheoryResearcher uses data to develop a theory that will explain what is observed. Researcher collects, codes, and analyzes data simultaneously.
13Epidemiological Research Concerned with the study of the distribution of disease, injury, or dysfunction in human populationsObservational Epidemiologic StudiesGather 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 outcomesCase-control studies – groups of individuals are selected on the basis of whether they have the disorder under studyCohort studies – group of individuals followed over time to determine if they will develop a disorder
14Nontraditional Designs: Examples Methodological DesignsUsed to develop research approaches or the R/V of instruments to measure constructs used as variables in researchSecondary AnalysisStudying data previously collected in another studyMeta-Analysis DesignsInvolves merging findings from many studies that have examined the same phenomenon