PS: Epidemiological Investigation Flashcards
What is prevalence?
Measuring existing cases.
What are the rates of prevalence?
It has none.
What is incidence rate?
Measuring new cases.
What is the main difference between prevalence and incidence?
Incidence is concerned with time, whereas prevalence isn’t.
How do you calculate incidence rate?
new events/ person x time
i.e. events per person per time
What is meant by person-years?
The sum of the total time of everybody followed up in a study.
Give an equation for prevalence.
Incidence x Duration of disease
Describe how the following would effect prevalence:
Increase the number of incidence.
Increased prevalence.
Describe how the following would effect prevalence:
Cure more patients.
Lower prevalence.
Describe how the following would effect prevalence:
Kill more patients.
Lower prevalence.
Describe how the following would effect prevalence:
Keep patients alive longer.
Increased prevalence.
What is the observed value?
The best estimate of the true or underlying tendency. It is used because the true value is impossible to acertain.
What is a valid interpretation of a p-value of <0.05?
It is reasonable to reject the stated null hypothesis as the observations are statistically significant.
NOTE: A p-value of >0.05 doesn’t mean that the hypothesis has been proven.
What is meant by the 95% confidence interval?
The range within which we can be 95% certain the true value of the underlying tendency really lies.
TRUE OR FALSE: The observed value can be within the confidence interval, or outside of it.
FALSE: The observed value is always within the confidence interval.
