1. Linking analysis methods
MEDI6302
Session 3
Linking analysis methods
to research questions
Sydney
Broome
Fremantle

2. question, design & analysis are linked
Research
question, design & analysis are linked
Analysis method
Research question
Research design
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

3. Analysis
method
Organises & presents data in systematic & understandable way
Tests the data to answer research question (hypotheses)
Analysis methods described in methods section of paper
Analysed data presented in results section
Three main research analysis methods are …
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

4. Analysis methods Qualitative -describes & interprets data Quantitative
-e.g. case reports, interviews, diaries
Quantitative
-organises, tests & presents data mathematically
-statistical approach
-basis of hypothesis testing
Mixed-methods
-combination of qualitative & quantitative methods
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

5. Qualitative research
Describes & interprets data to identify meanings & patterns, without using mathematics
Popular in social sciences
No hypothesis testing involved
Data gathering: observations, interviews, questionnaires, documents
Analysis methods: phenomenology, ethnography, grounded theory
Presentation: text, tables, diagrams
QR may lead to confirmatory quantitative studies
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

6. Qualitative methods of analysis
Phenomenology: in-depth interviews to describe how individuals experience a phenomenon
Ethnography: rich & holistic description of the culture of group under study
Grounded theory: development of a “bottom-up” theory based on data analysis, often collected by in–depth interviews
Case study: detailed accounts of one or more cases
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

7. Learning task 1 Qualitative methods
Provide an example of how qualitative research might be used to investigate a medical condition affecting a remote aboriginal community in WA?
Provide a historical example of how qualitative research was used to investigate a 19th century health-care problem?
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

8. Quantitative research
Descriptive statistics
-organises & presents data in a ‘comprehensible’ form
-frequency, central tendency (mean, mode median), spread (range, IQR, SD)
-presented as tables or graphs (histogram)
Comparative statistics
-differences between groups ( t-test, Chi square, ANOVA)
-associations between groups (correlation, regression)
-effect-size (NNT, odds ratio; relative risk, Forest plots)
-Basis of hypothesis testing
-Statistical significance & power
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

9. Descriptive statistical analysis
Learning task 2
Descriptive statistical analysis
Understand the role of descriptive statistics in data analysis
How is the central tendency of data analysed?
Understand the key features of a normal distribution
How is the spread of data analysed?
Understand interquartile range & ‘box-and-whisker plot’
How are descriptive data presented in a paper?
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

10. Statistical power & sample size
Power  probability of detecting a TRUE positive result
 probability of accepting a FALSE negative result
Power determines the sample size (and vice versa)
Affects research design: numbers, timeline, costs
Power calculation is always required
Power calculation must be reported in methods section
Consult a statistician EARLY about power
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

11. Learning task 2 Statistical power
What is a type I error (accepting a false positive)
What is a type II error (accepting a false negative)
What is the α-risk? (p of type I error; or the significance level; 0.05)
What is the β-risk? (p of type II error; 0.2)
What is 1 - β (Power; = 0.8)
What 3 factors affect power?
Statistical significance level (p <0.05), expected size of outcome, sample size
Calculate the sample size required for your research

12. End
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

13. Descriptive statistical analysis Data presented as: Tables Histograms
Distribution curves
Box-and-whisker plots
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

14. Distribution curve Frequency or Probability Outcome
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

15. Distribution curve derived
from histogram
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

16. Normal
distribution
Continuous probability curve of frequency of an outcome
© Eric J. Visser 2018 UNDA. All rights reserved V2.0

17. Power
Analysis
© Eric J. Visser 2018 UNDA. All rights reserved V2.0