| What is the definition of a census and what is it useful for | A simultaneous collection of demographic data of people at a specific area
Useful for :
Allocation of resources
To see trends in a population
Projection of the population |
| What is crude birth rate | Number of live births per 1000 population |
| What is General Fertility Rate | Number of live births per 1000 fertile women between the ages 14-55 ( better for calculating birth rates ) |
| How do you calculate the relative risk ( basic formula ) | Incidence risk of exposed group / incidence risk of unexposed group |
| How do you calculate Point prevalence | Number of cases at that time / Number of people at that time |
| How do you calculate Incidence Risk | Number of new cases in that specific time / Number of disease free people in that time |
| What is a confounding factor | A factor that is associated with both the outcome and exposure of intrest |
| How to calculate Standardised Mortality Rate | Observed number of deaths/ expected number of deaths x 100 |
| How do you calculate Incidence Rate | Number of new cases in a time period / (Number of total people x Follow up period) |
| How do you calculate Odds of exposure | Exposed cases / Unexposed cases |
| How do you calculate Odds Ratio | Odds of exposure in cases / Odds of exposure in control |
| What are some advantages of Case control Studies | Good for rare disease or long time for a disease to develop
Requires small sample size
Overcomes temporal delays
Cheap and quick |
| Advantages of Cohort Studies | Good for rare exposures
Possible to measure the incidence/risk directly
Reduced recall and selection bias |
| Disadvantages of Cohort Studies | Takes a long time
Large and resource intensive
Risk a high losses of follow up --> survivor bias
Not good for rare diseases |
| Disadvantages of Case Control Studies | Only possible to calculate OR
Recall, Selection and Information Bias
Sometimes difficult to be sure that exposure preceded disease |
| Advantages of RCT | Unbiased distribution of confounders
Blinding
Randomisation
Results are accurate becuase control group is used
Can make causal interferences |
| Disadvantages of RCT | Expensive --> time/money
Volunteer Bias
Ethically problematic at times |
| How can you spot Publication Bias in a systematic review or meta-analysis | Use a funnel plot, where you put the study size and whether it worked or not and see if there are any gaps |
| How do you interpret Forests Plots | Bigger the dot, the bigger the sample used
The line is the confidence interval while the vertical line intersecting with the lines of the plots show the Odds ratio ( position of the box )
- Basically if there is an intersection then the data is not statistically significant |
| What is Bradford Criteria used for? | Inferring causality Uses features such as association features, Exposure/outcomes and Other evidence |
| Advantages of systematic reviews | Avoids duplication of studies
High statistical power
High quality evidence
Useful when there are disparate findings among several studies |
| Disadavantages of systematic reviews | Publication bias
Requires access to various databases
Vairable quality of studies |
| How do you interpret the Confidence Interval | You look at whether the range of values of the CI has the null value of 1, if it does that means that you cannot reject the null hypothesis
Hence the data is statistically significant |
