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Epidemology
Term | Definition |
---|---|
Odds ratio | The level of exposure in a diseased group of animals divided by the level of exposure within a non-diseased group |
P-value | A level of significance which determines whether to reject or accept the hypothesis |
95% confidence interval | 95% confident that the population value lies within this range. Probability that the value will be accurate at a 95% confidence |
Sporadic | Irregular or haphazard occurrence of disease - related to environmental conditions |
Recall bias | When a farmer cannot remember the full details of an event which happened within the past - i.e. vaccinations, clinical signs |
Incidence | The number of new cases that occur in a known population over a specified period of time |
Prevalence | The number of instances of disease or infection in a known population at a designated time, without distinction between old and new cases. |
Case control study | A retrospective study which looks back to identify why disease occurred in some animals but not others. |
Confounding | Variables which can have an adverse effect on result (i.e. age, sex, breed) |
3 conditions which must be fulfilled for something to be a confounder in a study | 1 - be a risk factor for disease 2 - be associated with exposure 3 - not to be an intermediate step in the causal pathway |
Risk factor | A characteristic or exposure which increases the likeliness for disease |
Prospective | Something which can happen in the future |
Prospective cohort | Outcome has not happened yet, able to follow over time - providing more time for clinical signs to arise and be identified. Good for investigating rare exposures. |
Power (i.e. 80%) | The probability that it will reject a false null hypothesis |
What would need to happen to sample size if power needed to be at a higher level (i.e. 90% power) | Increase sample size |