Health and Disease in Populations Flashcards
What are censuses useful for? (3 things)
- allocating resources
- projecting populations
- observing trends in populations, e.g. Age and ethnicity
What is CBR?
Crude Birth Rate- number of live births per 1000 people
What is GFR?
General Fertility Rate- number of live births per 1000 women aged 15-44
What is TPFR?
Total Period Fertility Rate- average number of children born to a hypothetical woman in her life time.
What is the advantage of using TPFR
It isn’t influenced by age group structure
What is CDR?
Crude Death Rate- number of deaths per 1000 people
What is ASDR?
Age specific death rate- number of deaths per 1000 in age group.
What is SMR?
Standardised Mortality Rate - compares observed with expected values, adjusts for age-sex distributions and other confounders
Define incidence rate
The number of new cases of a disease per 1000 people per year
Define prevalence
The amount of people in a population who have a specific disease
What is IRR?
Incidence Rate Ratio - compares incidence rates of two populations with varying exposures, so relative risk can be calculated.
Define ‘confounding factor’
Something that is associated with both outcome and exposure, but is not part of the causal pathway
Why do we produce error factors and confidence intervals?
To account for variation
What is a P Value?
The probability of obtaining a test statistic
What is biasing?
The deviation of results from the truth via a certain process
What is selection bias? Give two examples.
Error due to the two groups being collected in a way with systematic differences , e.g. Allocation bias or healthy worker effect.
What is information bias? Give two examples.
Error due to systematic misclassification of subjects in the group e.g. Recall bias and publication bias.
What is a cohort study?
Recruitment of disease free individuals, classifying them according to their potential exposure and following them up for extend periods.
What kind of situations are cohort studies good for studying? (Two things)
Rare exposures and diseases which take a long time to develop.
What are the two main types of cohort study?
Prospective
Retrospective
What is the difference between internal and external comparisons?
Internal - compare sub cohorts who are either exposed or unexposed, calculate IRR
External- compare exposed with external reference population, calculate SMR
What 5 things must you write when evaluating a study in a exam question?
Can we reject the null hypothesis? State the p value State if H0 is with in the CI Are the results statistically significant? How many times more at risk?
What are case control studies?
Recruit disease free individuals and diseased individuals, then determining their exposure status. Then calculate an odds ratio.
How do you calculate an Odds Ratio?
(AxD/BxC) ( where cases and Controls are alphabetically across the top of the table, exposed and unexposed are alphabetically across the left of the table and the boxes are lettered a to d left to write and top to bottom)
