Designing your Research Designing your Research ProjectProject 

 Ivan J Perry

Department of Epidemiology & Public Health

University College Cor

Learning objectives• Understand the nature of science, with particular reference to the

core concept of measurement of causes and effects

• Explain the concept of hypothesis testing in quantitative research and understand the need to specify hypotheses in terms of measurement

 • Understand that epidemiological methods provide a conceptual

framework for the conduct of clinical and population based research.

• Understand the need to address bias,confounding and chance in designing your research project.

• Understand the importance of sampling and the concept of target populations, study populations and study samples

• List the major elements to be addressed in drafting a research protocol

ScenarioScenario

It is suggested that occupational exposure to volatile anaesthetic agents causes depression. You wish to test this hypothesis.

Seeking to understand the world by a process of observation or experimentation

Measurement - core activity

Measurement of causes and effects or exposures (gene and environment) and disease

To test hypothesis relating cause to effect

Hypothesis must be testable/capable of being disproved or refuted

In the late eighteenth century, Antoine Lavoisier, introduced the scientific approach to problem solving:

Theory

Hypothesis

Observations or Experiment

Interpretation

Results

Question or hypothesis: must be clearly stated (descriptive vs.. analytical research) Would qualitative methods be more appropriate?

Science/research: essentially an exercise in measurement

Study design: appropriate to question/hypothesis and feasible?

Prevalence of Asthma in children with and without pets at home.

Incidence of Diabetes in smokers and non-smokers

Be as specific as possible (e.g. Prevalence or Incidence)

Quantitative Study Designs

Randomised Controlled Trial

Case ControlCohort

Ecological Cross-sectional

How will exposure and outcomes be measured?

How will validity (accuracy) and reliability (precision) be determined?

Are established questionnaires/instruments available?

Need for standardised methods to minimise random error (chance) and systematic measurement error (measurement bias).

Define target population: -to whom will the findings apply

Study Population: -available for study -sufficiently representative of target

population

Study Sample: -representative (in statistical sampling terms) of study population

Concept of sampling: -variation/sampling error

Study population and study sample?

Methods of sampling: random, stratified, systematic, cluster, convenience.

Representativeness of sample (selection bias).

Methods of recruitment and expected response rate (selection bias)

Sample size (chance, type I and type II errors).

Data collection methods, questionnaires (interview or postal), physical measurements, blood tests.

Data to be collected (potential confounding variables).

EpiData/Microsoft Access

Avoid Microsoft Excel

Minitab/SPSS

Ethics Committee

Informed Consent

Confidentiality/Data Protection

Conflicts of Interests

Research Integrity