Definitions Flashcards
Prevelance
The amount of people in a set population who currently have that disease
(Doesn’t have a time frame)
General Fertility Rate
No of live births per 1000 fertile women aged 15-44
Crude Birth Rate
Number of live births per 1000 of the population
Total Period Fertility Rate
Average number of children born to a hypothetical woman in her lifetime
Age Specific Death Rate
Deaths per 1000 people in a particular age group
Confounding Factor
A confounder is associated with both the exposure and outcome of interest but does not lie on the causal pathway between exposure and outcome
What does an SMR do?
Compares a cohort to a reference population/general public
Why is an incidence rate a measure of absolute risk?
Because it is a rate/it is within a certain time frame
Define Census
Simultaneous recording of data of all people in a defined area at a particular time
How do you calculate an Incidence Rate Ratio? (IRR)
Rate unexposed
What would an SMR reading of greater than 100 suggest? (SMR>100)
This would suggest there is excess mortality in the cohort
What would an SMR of less than 100 suggest? (SMR
That there is less mortality in the cohort than in the general population
What would a positive IRR suggest?
That there is more death or incidence in the exposed group compared to the unexposed group.
The increased rate of disease is due to an increased rate of exposure
Interpret an IRR of 2.25
The exposed group are 2.25 times as likely to get…. Compared to those who were unexposed.
What would the NH be when you’re calculating risk difference?
0
Because same number-same number=0
If a P value is greater than 0.05…
- are the findings statistically significant?
- can you reject the null hypothesis?
The results are NOT statistically significant
You canNOT reject the NH
If the NH lies within the given confidence intervals, what will the P value be?
How would you interpret this?
P>0.05
Can’t reject NH as it could be a true value.
Not statistically significant
Incidence Rate
The number of new cases of a certain disease per 1000 of the population in a given amount of time
(Per thousand person years)
How would you adjust for confounders? (One way)
Use matched case-control
Where you match a case with a control who has the exact same date of birth and is same age etc etc
What effect on an odds ratio does selection bias have?
Underestimates odds ratio
What effect does information bias have on an odds ratio?
Shrinkage to null
What measure would you use for an internal cohort study?
IRR
What measure would you use for an external cohort study?
SMR
Why can case controls only give a relative risk?
Because they provide us with a ratio, not a rate
If more of the control people underestimated their exposure in a case control study, what would the effect on the association be?
Overestimate the association as it would make D value larger (numerator)
If more case people underestimated their exposure, what effect would it have on the interpretation of the association?
Underestimate association
What do you call it when both cases and controls randomly misclassify?
Shrinkage to null
Why is SMR good?
Accounts for confounders/takes them into account
