Quantitative Research

Objectives

DefinitionList typesDiscuss characteristicsExamine the types of designsHow quantitative relates toe evidence-based

nursingSummary points

Definition

Identified with the traditional scientific method

Gathers data objectively in an organized manner

Findings can be generalized to other situations/populations

Systematic plan

Types

Experimental designs Treatment Control group

Quasi experimental Lacks randomization May not have control group

Non experimental Generates questions for experimental designs

Characteristics

Why – Purpose for the studyWhere – Setting where the study is doneWho – Subjects to be studiedWhat – Type of data to be collectedWhen – Timing of the data collectionHow – Design used for the study

Experimental Design

ControlMost common and important

characteristicManipulation

Independent variable Randomization

Assignment of subjects to a group allowing for equal opportunity of selection

Variables

Dependent Outcome of the study Usually not manipulated

Independent Treatment, intervention, or experiment Usually manipulated

Extraneous Need to be controlled Examples – gender, age, ethnicity

Generalization

Ability to apply the results of a study to other settings and/or populations

Helps to strengthen the studyAided by careful control of the study through the use of randomization, control, and manipulation

Experimental Designs

Look for cause and effectMust be a preceding cause and a relationship

between the cause and outcomeIssues to consider

Can the variables be manipulated Ethics Feasibility Hawthorne effect

Types Pretest-posttest Randomized Controlled Trials (RCTs)

Non-Experimental Designs

Manipulation of variables is not possibleRandomization is not possibleObservational not interventionalTypes

Secondary analysis Meta analysis

Quasi-Experimental Design

Most frequently used quantitative research design

Independent variable is manipulatedNo randomization of subjectsNo control group usedNot as strong design as experimental Stronger design than descriptive More practical

Control

Critical for results related to cause and effect in relation to the treatment/intervention

Randomization aids in controlling extraneous variables

Areas of concern Maturation Attrition of subjects History

Descriptive Designs

Examines the characteristics of just one sample population

Used for theory development, practice problems, rationale for current practice or clinical decision making based on what others are doing

Types Comparative Time dimensional Cross-sectional Trends and events Correlational

Comparative Design

No manipulation of the independent variable

No control group used

Can be retrospective

Correlational Design

Most widely used descriptive designExamines the relationships between two or

more variables within a situationReason for the relationship is unknownDo not conclude that only one variable

causes anotherCan be prospective or retrospective in

designCan be predictive in nature

Quality Improvement Projects and Root Cause Analysis

Focused on patient outcomes Improving practice, not scientific inquiryRoot Cause Analysis

Examine systems Looks for reasons for system or person error Adverse events or sentinel events

Evidence-based Considerations

Increases comprehension of various designsConcepts of randomization and control are

essentialWhat is expected (relationships, effect, etc)

determines designThree essential components must be

present for experimental design – control of variables, manipulation, and randomization

Summary Points

Identified with traditional scientific methodsObjective, systematic plan for gathering dataDesign centers around why, where, who,

what, when and how questionsExamines relationships for cause and effect

Summary Points Contd.

Manipulation of the independent variable, control of extraneous variables, and randomization are essential

Comparative designs – no manipulation or control of the independent variable

Correlational design most commonly used descriptive design

Types of correlational studies – ex post factor, prospective, or predictive

Summary Points Contd.

Experimental designs look for cause and effect

Issues – ethics, manipulation of variable, feasibility, and Hawthorne effect

Most classic experimental design – pretest-posttest design

Randomized Controlled Trials – true experimental design

Summary Points Contd.

Types of non experimental designs used in EBP – secondary analysis and meta analysis

Quasi experimental designs used most frequently when no randomization or control group possible

Most commonly used quasi experimental design formats – non equivalent control group and time series designs

Non equivalent control groups design compares two groups without randomization

Summary Points Contd.

Time series design – no randomization, no control group, data collected at various intervals.

Threats to study – history, maturation, and attrition

Implications for EBP – must have working knowledge about quantitative designs.

Root Cause Analysis and Quality Improvement work to show relationships