241109 rm-j.p.-non experimental design

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  • Researchers are not in agreement on how to classify non-experimental studies. Some studies fall exclusively within one of these categories, whereas other studies have characteristics of more than one category.
  • Eg. Lauri, Lepisto and Kappeli (1997) assessed whether there were differences between patients and nurses in assessing hospitalized patients’ needs. The study compared the findings between the two groups revealing that there were many areas in which patient and nurses’ perceptions were different. This study did not manipulate the variables but assessed perceptions of patients’ need to provided data for future nursing intervention studies.
  • CORRELATIONAL STUDIES Examines the relationship between 2 or more variables Researcher not testing if 1 variable causes another or how different 1 variable is from another. Researcher is testing if variables covary, ie. As one variable changes, does a related change occur in the other variable. NOTE it is a very useful design for clinical research studies because many of the phenomena of clinical interest are beyond the researcher’s ability to manipulate, control and randomize. For instance, a researcher interested in studying the grief experiences of women who have recently miscarried could not randomly assign subjects to grief and non-grief groups. Also the experience of a miscarriage is a naturally occurring process and as such cannot be manipulated.
  • 241109 rm-j.p.-non experimental design

    1. 1. Nonexperimental Design-an overview By Dr. Jayarani Premkumar Professor & Head Medical Nursing Department College of Nursing CMC, Vellore
    2. 2. Introduction Research Design Research design is a set of decisions that make up the master plan specifying the methods and procedures for collecting and analyzing the needed information
    3. 3. Design chosen depends on <ul><li>Type of problem </li></ul><ul><li>Knowledge already available about the problem </li></ul><ul><li>Resources available for the study </li></ul>
    4. 4. A Continuum of Quantitative Research Design <ul><li>l_____________l_____________l </li></ul>Non-experimental Quasi-experimental Experimental
    5. 5. Purposes of Non experimentaltal research design <ul><li>Exploration and description of phenomena in real life situations </li></ul><ul><li>Used to develop theory </li></ul><ul><li>Identify problems </li></ul><ul><li>Make decisions /determine what others in similar situations are doing </li></ul>
    6. 6. Critical Thinking Decision Path: Non experimental Design Choice
    7. 7. Classification of Non Experimental designs : <ul><li>Descriptive/exploratory survey studies </li></ul><ul><li>Interrelationship/difference </li></ul><ul><ul><li>Correlational studies </li></ul></ul><ul><ul><li>Ex post facto studies </li></ul></ul><ul><ul><li>Prediction studies </li></ul></ul><ul><ul><li>Developmental studies </li></ul></ul><ul><ul><ul><li>Cross-sectional & longitudinal studies </li></ul></ul></ul><ul><ul><ul><li>Retrospective & prospective studies </li></ul></ul></ul>
    8. 8. Descriptive research <ul><li>Descriptive research provides answers to the questions of: </li></ul><ul><ul><li>Who </li></ul></ul><ul><ul><li>What </li></ul></ul><ul><ul><li>Where </li></ul></ul><ul><ul><li>When </li></ul></ul><ul><ul><li>How </li></ul></ul><ul><li>Cannot answer the question Why? conclusively </li></ul>
    9. 9. Reasons for Undertaking Non-experimental Studies <ul><li>Number of human characteristics/ independent variables are not subject to experimental manipulation or randomization </li></ul><ul><li>Some variables cannot ethically be manipulated </li></ul><ul><li>For some research, it is not practical to conduct a true experiment/manipulate variables </li></ul>
    10. 10. Reasons -Cont’d <ul><li>For some situations, it is more realistic to explore phenomena in more natural manner </li></ul><ul><li>Non-experimental research is often needed to scope out the experimental one </li></ul>
    11. 11. Key Characteristics <ul><li>A research design in which a researcher observes a phenomenon without manipulating the independent variables (s) </li></ul><ul><li>No manipulation </li></ul>
    12. 12. Key Characteristics-cont’d <ul><li>Independent variables have already occurred, so no control over them </li></ul><ul><li>Clear, concise problem statement that is based on a theoretical framework, or natural phenomenon. </li></ul>
    13. 13. Descriptive Research <ul><li>Types: </li></ul><ul><ul><li>Descriptive Correlational Studies </li></ul></ul><ul><ul><li>Univariate Descriptive Studies </li></ul></ul><ul><ul><ul><li>Prevalence Studies </li></ul></ul></ul><ul><ul><ul><li>Incidence Studies </li></ul></ul></ul>
    14. 14. Descriptive Research <ul><li>Purpose is to </li></ul><ul><ul><li>observe, describe, & document aspects of a situation as it naturally occurs </li></ul></ul><ul><ul><li>serve as a starting point for hypothesis generation or theory development </li></ul></ul>
    15. 15. Descriptive/Exploratory Survey <ul><li>Broadest category </li></ul><ul><li>Detailed observations, descriptions & documentation of existing variables </li></ul><ul><li>Little is known about the phenomenon </li></ul><ul><li>Justifies, assesses current conditions/practice </li></ul><ul><li>Variables of interest: opinions, attitudes or facts </li></ul>
    16. 16. Descriptive/Exploratory Survey-cont’d <ul><li>Data collected by questionnaire or interview </li></ul><ul><li>Determines differences between variables </li></ul><ul><li>Researchers only relate one variable to another, no attempt to determine causation </li></ul>
    17. 17. Exploratory Survey Research <ul><li>Designed to obtain information about : </li></ul><ul><ul><li>prevalence </li></ul></ul><ul><ul><li>distribution </li></ul></ul><ul><ul><li>interrelations of variables within a population </li></ul></ul><ul><li>Census vs. sample surveys </li></ul>
    18. 18. Exploratory Survey Research-cont’d <ul><li>Self-reporting </li></ul><ul><li>Flexibility and broadness </li></ul><ul><li>Superficiality – extensive vs. intensive analysis </li></ul>
    19. 19. Descriptive survey consists of four major stages <ul><li>Selecting an appropriate sample </li></ul><ul><li>Planning and developing instrumentation </li></ul><ul><li>Administering the instrument and data collection </li></ul><ul><li>Analysing the findings </li></ul>
    20. 20. Descriptive/Exploratory Survey (cont’d) <ul><li>Advantages: </li></ul><ul><ul><li>large amount of information can be </li></ul></ul><ul><ul><li>obtained from a large population in an </li></ul></ul><ul><ul><li>economical manner which is “surprisingly” accurate </li></ul></ul><ul><ul><li>Survey content is flexible and scope is broad </li></ul></ul>
    21. 21. Advantages cont’d <ul><li>Subjects have greater sense of anonymity and may respond with more honesty </li></ul><ul><li>Questions are predetermined and standardized for all subjects, minimizing research bias </li></ul><ul><li>Large sample sizes are possible </li></ul><ul><li>A large volume of data can be collected </li></ul>
    22. 22. Descriptive/Exploratory Survey (cont’d) <ul><li>Disadvantages </li></ul><ul><ul><li>Information tends to be superficial as breadth is emphasized </li></ul></ul><ul><ul><li>Expertise in: sampling techniques, questionnaire construction, interviewing and data analysis to produce a reliable and valid study. </li></ul></ul><ul><ul><li>Time-consuming & sometimes costly </li></ul></ul>
    23. 23. A strong descriptive design should: <ul><li>Include procedures that enhance the probability of generating trust worthy data </li></ul><ul><li>Demonstrate appropriateness for the purpose of the study </li></ul><ul><li>Be feasible given the resource available to the researcher and existing constraints </li></ul><ul><li>Incorporate steps that are effective in reducing threats to validity </li></ul>
    24. 24. Univariate Descriptive Studies <ul><li>Could focus on one or more variables </li></ul><ul><li>Undertaken to describe the frequency of occurrence of a behavior or condition or each variable rather than relationships between or among them </li></ul><ul><li>Types: </li></ul><ul><ul><ul><ul><ul><li>Prevalence Studies </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Incidence Studies </li></ul></ul></ul></ul></ul>
    25. 25. Prevalence Studies <ul><li>Done to determine the prevalence rate of some condition at a specific point in time </li></ul><ul><li>Data is obtained from the population at risk for the condition – cross sectional design </li></ul><ul><li>Prevalence Rate (PR) = # cases with condition X K </li></ul><ul><li> # in population at risk </li></ul>
    26. 26. Incidence Studies <ul><li>Used to measure the frequency of developing new cases </li></ul><ul><li>Need longitudinal designs </li></ul><ul><li>Incidence Rate (IR)= </li></ul><ul><li># new cases with condition over given period X K </li></ul><ul><li># at risk of becoming a new case </li></ul>
    27. 27. Incidence Studies-cont’d <ul><li>Relative Risk: </li></ul><ul><li>an estimate of risk of “caseness” in one group vs. another; </li></ul><ul><li>contribution of risk factors </li></ul><ul><ul><li>E.g. males vs females for acquiring depression </li></ul></ul>
    28. 28. Interrelationship/Difference Studies: Ex Post Facto Studies <ul><li>Literally means ‘from after the fact’ </li></ul><ul><li>Also known as causal-comparative studies or comparative studies </li></ul><ul><li>Explores differences/relationships between variables (similar to quasi-experimental designs) </li></ul>
    29. 29. Ex Post Facto Studies-cont’d <ul><li>Advantages: </li></ul><ul><ul><li>Allows for establishment of a differential effect </li></ul></ul><ul><ul><li>Similar to correlational designs </li></ul></ul><ul><ul><li>Offers a higher level of control </li></ul></ul>
    30. 30. Ex Post Facto-cont’d <ul><li>Disadvantages: </li></ul><ul><ul><li>Lack of control on variables </li></ul></ul><ul><ul><li>Unable to draw causal linkage </li></ul></ul><ul><ul><li>Problem of alternative hypothesis </li></ul></ul>
    31. 31. Comparative descriptive design Group 1 (variables measured) Describe Group ii (Variables measured) Comparison of Groups on Selected variables Describe Development Of hypothesis Describe Interpretation Of meaning
    32. 32. Interrelationship/Difference Studies: Correlational Studies <ul><li>Examines if variables co vary </li></ul><ul><li>Quantifies the strength or relationship between the variables ( not cause & effect) </li></ul><ul><li>+ve or –ve direction relationship determined </li></ul>
    33. 33. Correlational Studies <ul><li>Advantages: </li></ul><ul><ul><li>Increased flexibility when investigating complex relationships among variables </li></ul></ul><ul><ul><li>Efficient and effective method of collecting a large amount of data </li></ul></ul><ul><ul><li>Potential for practical application in clinical settings </li></ul></ul>
    34. 34. Advantages-cont’d <ul><ul><li>Potential foundation for future, experimental studies </li></ul></ul><ul><ul><li>Framework for exploring relationships that are not manipulated . </li></ul></ul>
    35. 35. Correlational Studies - Cont’d <ul><li>Disadvantages : </li></ul><ul><ul><li>Unable to manipulate variable of interest </li></ul></ul><ul><ul><li>No randomization in sampling </li></ul></ul><ul><ul><li>Generalizability decreased as dealing with preexisting groups </li></ul></ul><ul><ul><li>Unable to determine a causal relationship because of the lack of manipulation, control and randomization. </li></ul></ul>
    36. 36. Descriptive Correlational Studies <ul><li>Describes the relationship among variables rather than infer cause-and-effect relationships </li></ul><ul><li>Are usually cross-sectional </li></ul>
    37. 37. Interrelationship/Difference Studies: Developmental Studies <ul><li>Not only concerned with existing status & interrelationship of phenomena but also with changes from elapsed time. </li></ul><ul><li>Cross sectional -one/more time points, perhaps different groups </li></ul><ul><li>Longitudinal :several time points with same group over extended period </li></ul>
    38. 38. Developmental Studies-cont’d <ul><li>Retrospective : dependent variable has already been affected by independent variable & link present events to past events </li></ul><ul><li>Prospective : link present events to presumed future effect, </li></ul><ul><li>less common, </li></ul><ul><li>considered stronger design </li></ul>
    39. 39. Longitudinal /prospective studies <ul><li>Data is collected from the same group at different points in time </li></ul><ul><li>It explores differences and relationships </li></ul><ul><li>It is also referred to as repeated measures or cohort studies </li></ul>Time 1 Measure variables Sample 1 Time 2 Measure variables Sample2 Time 3 Measure variables Sample3
    40. 40. Strength of Longitudinal studies <ul><li>Capture historical trends and explore causal associations </li></ul><ul><li>Retrospective studies are cost effective and cost –efficient </li></ul><ul><li>Prospective studies can document that a causal factor precedes an outcome, strengthening hypothesis about causality </li></ul><ul><li>Prospective studies provide the opportunity to measure characteristics and events accurately and do not relay on recall </li></ul>
    41. 41. Limitations of longitudinal studies <ul><li>Attrition rates and the potential loss of subjects over time </li></ul><ul><li>Dependent on accurate, complete secondary data or the subjects ability to recall past events </li></ul><ul><li>Expensive </li></ul><ul><li>Conclusions may be based on a limited number of observations </li></ul>
    42. 42. CASE (S) STUDY <ul><li>The researcher will take a case (s) study and analyze in depth </li></ul><ul><li>Relate to other factors </li></ul><ul><li>Improves details and understanding of causes and effect but lacks generalization. </li></ul>
    43. 43. Strengths of case studies <ul><li>Provide in depth information about the unique nature of individuals </li></ul><ul><li>Responses and changes emerge over time can be captured and appraised </li></ul><ul><li>New insights can be obtained and potentially generate additional studies </li></ul>
    44. 44. Limitations of case studies <ul><li>No baseline measurement to provide comparison with the intervention outcome </li></ul><ul><li>Difficult to determine if there is an improvement in outcome </li></ul><ul><li>Researcher objectivity is required </li></ul><ul><li>Results cannot be generalized to larger populations </li></ul>
    45. 45. Epidemiologic Research Designs <ul><li>Cohort studies : </li></ul><ul><li>Is a trend study in which specific subpopulations (e.g. age specific) are examined over time for generational differences </li></ul><ul><ul><li>prospective & retrospective </li></ul></ul>
    46. 46. Epidemiologic Research Designs-cont’d <ul><li>Case-control study : comparison of cases/subjects (with specific condition), with controls (without condition); only difference should be exposure to presumed cause </li></ul><ul><li>Cross-sectional design : phenomena under study are captured during one period of data collection; one point in time </li></ul>
    47. 47. Other designs <ul><li>Natural Experiments : </li></ul><ul><li>study of a group exposed to natural or other phenomenon that have health or other consequences, compared with a nonexposed group; people are affected at random </li></ul>
    48. 48. Others-cont’d <ul><li>Path Analytic Studies : </li></ul><ul><li>using a technique called path analysis, non experimental data is tested against a hypothesized causal inference </li></ul>
    49. 49. Social class Family Size School Achievement Ability Self esteem e1 e2 e3 Example of Path Analysis
    50. 50. Continuum of designs for inferring causality <ul><li>Strongest Weakest </li></ul><ul><li>Design Non Experimental Designs Design </li></ul><ul><li>_______________________________________ </li></ul>True Experimental Design Quasi Experimental Design Pre Experimental Design Natural Experiment Path Analytic Design Prospective Correlational Retrospective Correlational Descriptive Designs
    51. 51. Cont’d
    52. 52. Finding from descriptive studies can be used to support <ul><li>Assessment of patients and patient care </li></ul><ul><li>Diagnosis of patient care conditions </li></ul><ul><li>Care planning </li></ul><ul><li>Nursing interventions </li></ul><ul><li>Evaluation of outcomes </li></ul>
    53. 53. Summary <ul><li>The purpose of descriptive research is the exploration and description of phenomena in real life situation </li></ul><ul><li>Is used to develop theory, identify problems ,provide information for decision making </li></ul>
    54. 54. Summary-cont’d <ul><li>Nonexperimental research is research that lacks manipulation of the independent variable by the researcher </li></ul><ul><li>The researcher studies what naturally occurs or has already occurred </li></ul><ul><li>The researcher studies how variables are related. </li></ul><ul><li>Despite its limitations for studying cause and effect (compared to strong experimental research), non experimental research is very important in education. </li></ul>
    55. 55. THANK YOU

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