1. Sampling and Data Collection
Research Methodologies
in Allied Health
Peg Bottjen, MPA, MT(ASCP)SC

3. Research Process Planning Hypothesis or Aims Research Design
Data collection
The research process involves:
Planning for the project
Forming a hypotheses
Selecting a research design
Collecting the data
Organizing the data and presenting the data
Analyzing the data with statistical methods
Interpreting the data and forming conclusions
At this point depending on the findings, revising or adding to the research project may be necessary and that goes back to the planning stage. You will be going through this process as you work in your groups to prepare a research proposal.
Organization and Presentation of Data
Data Analysis
Interpretation and Conclusions

4. Objectives Upon completion of this unit the student will be able to:
• Outline advantages and disadvantages of three sampling methods • Operationally define the variables in a study • Identify limitations in research studies • Choose the method of data collection that best facilitates proving or disproving a hypotheses or best answers a research question • Explain how a test can be valid yet not reliable.

5. Boundaries of the Study
Define the terms
Dictionary definitions
ex. BMI – wt (kg) / ht2 (m)
Reference to a definition
ex. NHANES II study
Operational definitions
ex. obesity >95th percentile

6. Operational Definition
The operational definition of a variable is a statement of how the researcher in a particular study chooses to measure the variable in question.

7. More Boundaries of the Study
Assumptions
Scope
Limitations
Subjects

8. Sampling
Target Population
Representative Sample X X X X X

9. Representative Sampling Methods
Randomized – roll of dice
Area - location
Systematic – choose from list (every 5th)
Volunteer – ask for participants
Convenience – what is available

10. Subjects
Inclusion
Exclusion

11. Sample Size It depends! Procedures used to collect data
Statistical level of significance
Statistical power
Effect size

12. External Validity
The extent to which the results of an investigation can be generalized to other samples or situations.
Polgar & Thomas-4th Ed. 2001

13. Internal Validity
The intervention was responsible for the differences or lack of differences observed.

14. Data Collection Methods
Questionnaire
Interview
Observation
Measurement / instrumentation

15. Questionnaire Define information needed Draft questions Do pilot
Redraft
Administer questionnaire

16. Questionnaire Open vs Closed questions Scaled questions or statements
Likert scale
Strongly disagree, disagree, no opinion, agree, strongly agree
Semantic differential
Draw an x at point that best describes your feeling
Powerless Powerful X

17. Interview
Structured
Unstructured

18. Observation Who is observer Setting of observation
Use of instrumentation

19. Observation Complete participant Participant as observer
Observer as participant
Complete observer

20. Measurement / Instrumentation
Subjective measurements
Ratings or judgments by humans of quantities or qualities
Objective measurements
Measurement of physical quantities or qualities by equipment

21. Measurement / Instrumentation
Objective measurement
Data collected by instrumentation
Eg. Blood glucose, MR/CT scans, radiographic image, nuclear medicine scan, activated clotting time (ACT), nutrition screening instrument, stained slide read by expert
Data collected by standardized tests
Eg. SAT, ACT, GRE, CAT, Myers-Briggs, IQ test, patient quality of life (SF-36)

22. Desirable Properties of Measurement Tools
Reliability
Validity
Applicability
Practicality

23. Reliability - Precision
The test or assessment measures the same thing every time and results in the same answer every time.
Test-retest – correlates 1st to 2nd
Inter-observer – between different observers
Internal consistency – between items measured

24. Validity - Accuracy
The test or assessment measures what it claims to measure.
Sensitivity - % true positive
Specificity - % true negative
Test Result
Disease Present
Disease Absent +
True +
False + -
False -
True -

25. Validity of Mammography
Mammography Result
Known Breast Cancer +
169 ( true +) -
49 (false -)

26. Validity Predictive value
Ability of a measurement to predict the value of it or another test in the future (prognosis)
What is predictive value of an ACT score to your grade point average in college?

28. Summary Boundaries of the study Sampling Data Collection Methods
Reliability/ Validity

29. Critical Evaluation of Research
Who comprised the sample?
What was the inclusion criteria?
What was the exclusion criteria?
Was the sample biased?
How is the independent variable defined?
How is the dependent variable defined?
How were validity issues addressed?
How were reliability issues addressed?

30. Group Work
Questions 9 – 16 in the Research Proposal Notebook are designed to lead you through the process of the literature review, defining the research question, and selecting a research design. Answer each question in your group. Submit your results as described under Assignments.