Chapter 6 Selecting a Design

Research Design The overall approach to the study that details all the major components describing how the research will be carried out.

The Basis for Design Selection Purpose to be achieved Ethical limitations Measurements needed Researcher resources and skills Timeframe Amount of control required Ultimate audience

Three Phases of Design Identify assumptions about the knowledge to be gained from the study Select a design that serves the purpose of the study Develop detailed plans for implementation of the study

Assumptions about Knowledge Needed Quantitative –Measure effectiveness of interventions –Test a theory of relationships –Describe a phenomenon with objective precision Qualitative –Understand social relationships –Determine the meaning of events and phenomenon

Both Kinds of Research… Characterized by rigorous attention to scholarly nature of work Aim for reliability and trustworthiness of results Have a goal of generating credible evidence that nurses can use with confidence

Classifications of Designs Exploratory – Often qualitative or mixed methods. Can be quantitative if measurement used. They explore & describe a phenomenon Confirmatory – Relationship between variables has been posed & study designed to examine the hypothesis

Types of Variables Descriptive – characteristics that describe the sample. They are not manipulated Independent – The intervention; the “cause” of “cause” & “effect” Dependent – The outcome; the “effect of “cause” and “effect”. It is dependent on the intervention Extraneous – Factors that could have an effect on the outcome, but not part of the planned design. Also called confounding

Qualitative Concepts Design driven by nature of information to be gained Research should articulate: –Concepts of interest –Theories about relationships –Processes of interest Reflects the researcher/s’ tradition: –Phenomenology –Ethnography –Grounded Theory; See pg. 140

Descriptive Research Research designed to describe in detail some process, event, or outcome. The design is used when very little is known about the research question.

Research that Examines Relationships Correlation research –Quantifies strength and direction of a relationship Predictive research –Search for variables that can explain or predict an outcome

Descriptive Designs Survey design – Describes characteristics of subjects Cross-sectional study – Describes characteristics of sample at a single point in time Longitudinal study – Describes characteristics over time Case study Explores in depth one person, program or event See Table 6.2 pg. 139

Common Descriptive Designs Single subject – Studies the response of one person to an intervention Phenomenology – Studies the meaning of experiences Ethnography – Study of a given culture with immersion in the natural setting

Designs Describing Relationships Correlation – Relationship of 2 variables in 1 population or 1 variable in 2 populations Predictive – Relationship between predictive variable/s & outcome Grounded Theory – Develop a theory of process, action, or interaction. Studies social processes Tests of Model of Fit – Tests theories of causal relationship fitting data into preconceived model See Table 6.3 pg. 141

Design Criteria for Causality Temporality –Cause must precede the effect Influence –Must establish the probability that the cause influenced the outcome Control Specificity –All rival explanations are ruled out

Criteria for Experiment Randomization is used to select subjects and to place assign subjects to groups Must have a control group Must have an intervention Note: If 1 or more of the 3 criteria are missing the study is considered quasi- experimental. The most often missing element is randomization.

Designs to Examine Causality Experiment – Randomization, control or comparison, & intervention Quasi-experimental – Missing at least 1 element of an experiment Causal Comparative/Case Control – Nonexperimental groups are selected because they do or do not have a characteristic & examined for dependent variable/ groups closely matched based on independent variable See Table 6.4 on pg. 143

Designs to Examine Causality (Cont.) Time Series Analysis – Studies effects of intervention by measuring baseline, implementing intervention, and collecting data about the outcome at specified periods See Table 6.4 on pg. 144

Comparative Effectiveness Designs Observational – Population is assigned to alternative interventions & observed for outcome/s Adaptive – Patients assigned randomly to a treatment which is modified to increase efficiency & patients will probably benefit Pragmatic – Inclusion criteria widened & flexibility in application of intervention to improve relevance of results See Table 6.5 on pg. 145

Bias in Research True findings distorted due a factor other than the one studied May be due to: –Researcher –Measurements –Subjects –Procedures –Analysis –Extraneous Variables

Comparative Effectiveness Answer real-world questions Encompasses generation of evidence and its synthesis Relies on observational studies Responds to demand for evidence that is immediately useful and rigorous

A Research Plan Sampling strategy Measurement strategy Data collection plan Data analysis plan

A Good Methods Section… Provide a thorough, accurate account of every important step Provides enough detail to support replication Allows comparison of results across studies

Critiquing Research Design is clearly identified Rationale is provided or implied Characteristics of the design relate to the research question Variables are identified & defined Enough detail is given so a subsequent researcher could replicate the study If qualitative basis for emergent decisions are documented