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

question, design & analysis are linked Research question, design & analysis are linked Analysis method Research question Research design © Eric J. Visser 2017 UNDA. All rights reserved

Analysis method Determined by the research question & design Organises & presents data in systematic & understandable way Tests data to answer research questions (hypotheses) Described in methods section of paper Data analysis is presented in results section Three main research analysis methods are … © Eric J. Visser 2017 UNDA. All rights reserved

Analysis method 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 2017 UNDA. All rights reserved

Qualitative analysis Describes & interprets data to identify meanings & patterns, without using mathematical analysis Popular in social sciences No hypothesis testing involved Data gathering: observations, interviews, questionnaires, documents Analysis methods: phenomenology, ethnography, grounded theory Presentation: text, tables, diagrams Qualitative research may lead to confirmatory quantitative studies

Qualitative methods 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

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 2017 UNDA. All rights reserved

Quantitative methods Descriptive statistics -organises & presents data in ‘digestible’ form -e.g. frequency, central tendency, spread -presented in tabular or graphical form Comparative statistics (probability TESTING: significance, effect size) -differences between groups (e.g. t-test, Chi square, ANOVA) -associations between groups (e.g. correlation, regression) -effect-size (e.g. NNT, Forest plots) -basis of hypothesis testing

Descriptive statistical analysis Learning task 2 Descriptive statistical analysis Understand the role of descriptive statistics in data analysis How are descriptive statistical data presented in a paper? How is the central tendency & spread of data analysed? Draw & understand key features of a normal distribution Understand interquartile range & ‘box-and-whisker plot’ © Eric J. Visser 2017 UNDA. All rights reserved

Statistical power & sample size Probability of rejecting Null hypothesis when H1 is TRUE Reduces risk of a false negative result (type II error) Determines sample size Power calculation is always required in quantitative research Can be performed before or after a study is completed Must be reported as part of trial design Informs the research design, logistics, timeline, viability Consult a statistician EARLY about power analysis © Eric J. Visser 2017 UNDA. All rights reserved

Power Analysis © Eric J. Visser 2017 UNDA. All rights reserved

Learning task 2 Statistical power & sample size Define type I & type II error What is the β-risk? What is the α-risk? What is the meaning of 1-β? What three factors affect statistical power? How will you report power analysis in your paper? Calculate the sample size required for your research

End © Eric J. Visser 2017 UNDA. All rights reserved

Descriptive statistical analysis Data presented as: Tables Histograms Distribution curves Box-and-whisker plots © Eric J. Visser 2017 UNDA. All rights reserved

Distribution curve Frequency or Probability Outcome © Eric J. Visser 2017 UNDA. All rights reserved

Distribution curve derived from histogram © Eric J. Visser 2017 UNDA. All rights reserved

Normal distribution Continuous probability curve of frequency of an outcome © Eric J. Visser 2017 UNDA. All rights reserved