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Fundamentals of Epidemiology
&Biostatistics
Dr Eva Batistatou
Outline of this presentation…
What is epidemiology?
The Fundamentals of Epidemiology course
What is biostatistics?
The Biostatistics course
What is Epidemiology?
Origin of the term:
epi (upon) + demos (people) + logy (study of)
What is Epidemiology?
Definition:
e.g.
‘The study of the distribution and determinants of disease frequency in man’
MacMahon & Pugh (1970)
One of the pioneers of epidemiology due to his study of cholera in London in 1854.
John Snow
(1813-1858)
Importance of Epidemiology in Public Health
Epidemiology provides the basis for describing and explaining disease occurrence in a community
Examples of epidemiological questions:
How many new cases of AIDS were reported among teenagers in USA last year?
We might want to compare the number of reported cases to numbers in prior years to get a sense of whether AIDS is increasing or decreasing in this age group.
The number of reported new cases of AIDS is almost three times higher in young adults, 20-24years of age, compared to teenagers.
…seeking an explanation for the difference into behaviors/factors that differ between the age groups eg sexual activity, intravenous drug use.
Importance of Epidemiology in Public Health
Also…
Epidemiology provides a basis for developing, prioritizing, and evaluating public health programs
Examples of epidemiological questions:
What problems are present in the community?
What problems have the greatest public health impact?
Are adequate health services available and accessible?
Is a specific public health program successful?
Risk
The probability of disease developing in an individual in a specified time interval
Association
The relationship between an exposure or risk factor and an outcome
Bias and confounding
Systematic errors in the collection or interpretation of data that must be minimised
Causation
Establishing that the association between an exposure and an outcome is causal
Descriptive studies
Describe the distribution of disease in relation to person, place and time
Case-control studies
What is the likelihood of exposure in people with disease compared with people without disease?
Cohort studies
What is the likelihood of developing disease for people who are exposed compared with people who are not exposed?
Intervention studies
What is difference in outcome among people who received the intervention compared to people who did not?
On completion of the FOE unit you should be able to:
Calculate incidence and prevalence rates
Outline the advantages and disadvantages of descriptive studies, case-control studies, cohort studies and interventional studies
Calculate the appropriate effect measures within these study designs such as the OR and the RR
Understand the types of bias that can occur in observational studies
Understand the impact that bias, confounding and effect modification can have on observational studies
Perform direct and indirect age standardisation
Understand the principles of routine epidemiological surveillance and screening
What do we need to answer our epidemiological questions?
Data!!!
And then…what?
What is Biostatistics?
It is the science which deals with development and application of the most appropriate methods for the:
Collection of data
Presentation of the collected data
Analysis and interpretation of the results
Making decisions on the basis of analysis
Collection of data
Sources of data
Records Surveys Experiments
Types of data
Constant Variable
s
Types of Variables
Qualitativee.g. favourite colour
Quantitative
Discretee.g. shoe size
Contin.e.g. height
Presentation of the collected data
Presentation of the collected data
Manchester Children’s Growth and Vascular Health Study data
On completion of the Biostats unit you should be familiar with:
the concepts on which statistical methods are based
different types of data and different types of statistical tests
statistical analysis using a statistical package (e.g. Excel, StatsDirect, SPSS)
focus on understanding and interpreting the output from a statistical package
And also…
Descriptive statistics: mean, median, standard deviation, confidence intervals etc
Hypothesis tests: z-test, t-test, Mann-Whitney, chi-square etc
Sample size, correlation and simple linear regression
Multiple linear regression and logistic regression
Survival analysis
Assignments
Assignment 1
- Week 5 (30% of final mark)
Assignment 2
- Week 10 (70% of final mark)
Overall score0-40% Fail40-50% Diploma pass50-70% Masters pass70-100% Distinction pass
Recommended reading
Raj Bhopal (2002) Concepts of Epidemiology: an integrated introduction to the ideas, theories, principles and methods of epidemiology
Kirkwood and Sterne (2003) Essential Medical Statistics