HaDPop

Question 0

What is a census useful for?

Answer 0

Allocation of resources
Projections of populations
Trends in populations such as ethnicity

Question 1

What is a census?

Answer 1

The simultaneous recording of demographic data to all persons in a defined area

Question 2

What is the crude birth rate?

Answer 2

The number of live births in a population per thousand people

Question 3

What is the general fertility rate?

Answer 3

The number of live births per 1000 fertile women aged 15-44

Question 4

What is the total period fertility rate?

Answer 4

The average number of children born to a hypothetical woman in her lifetime

Question 5

What is the incidence rate

Answer 5

The number of NEW cases of a disease in a population per thousand people per year

Question 6

What is the prevalence?

Answer 6

The number of people in a population who currently have a disease

Question 7

What is a confounding factor?

Answer 7

Something that is associated with both the outcome and the exposure of interest, but is not the causal pathway between the exposure and outcome.

Question 8

How is the standard mortality ratio calculated?

Answer 8

(Observed number of deaths ➗ expected no of deaths) ✖️ 100

Question 9

What is variation?

Answer 9

When there is a difference between the observed value and the actual value?

Question 10

What do the confidence intervals indicate?

Answer 10

The range of values that we can say, with confidence, that the actual values will lie in between this range, in 95% of cases

Question 11

How are the upper and lower bounds of the confidence intervals calculated?

Answer 11

Upper: value ✖️ error factor
Lower: value ➗ error factor

Question 12

What do you do with the null hypothesis if the p>0.05

Answer 12

Insufficient evidence to reject our null hypothesis

Ie cannot reject null hypothesis (but can never accept it)

Question 13

What do you with null hypothesis if p<0.05

Answer 13

Sufficient evidence to reject our null hypothesis

Data is inconsistent with the null hypothesis and cannot be put down to chance

Question 14

What is selection bias?

Answer 14

Error due to systematic differences in the ways in which the two groups were collected

Question 15

What are the two types of selection bias?

Answer 15

Allocation bias

Healthy worker effect

Question 16

What is information bias?

Answer 16

Error due to systematic misclassification of subjects in the group

Question 17

What are the two types of information bias?

Answer 17

Recall bias

Publication bias

Question 18

What is bias?

Answer 18

Deviation of the results from the truth, via certain processes. Seen in epidemiology

Question 19

What does a cohort study involve?

Answer 19

Recruiting disease-free people and classifying them according to their exposure status.
Then followed up for extensive periods, disease progress is monitored and incidence rates are calculated.

Question 20

What are cohort studies good for?

Answer 20

Rare exposures
If a disease takes a long time to develop
Can look at different potential outcomes for one exposure
Allow calculation of a specific absolute risk

Question 21

What is a prospective study?

Answer 21

When disease free individuals are recruited and followed up

Question 22

What is a retrospective study?

Answer 22

Disease free people are recruited and their exposure status is calculated from historical documentation and followed up.

Question 23

What are internal comparisons in a cohort study? What ratio does it use?

Answer 23

When you have sub-cohorts within the original group and then compare exposed and unexposed within the cohort
IRR

Question 24

What is an external comparison? What ratio does it use?

Answer 24

When you have your exposed population compared against an external reference population. SMR

Question 25

What is the healthy worker effect?

Answer 25

Where there is basing of the results when a study involves workers compared to a reference population. Form of SELECTION bias because an employed individual is more likely to be healthy than an unemployed individual.

Question 26

What does a case control study involve?

Answer 26

Recruiting disease free individuals (controls) and diseased individuals (cases). Their exposure status is then determined using an odds ratio.

Question 27

What is the null hypothesis in an odds ration equal to?

Answer 27

1

Question 28

What are case-control studies useful for?

Answer 28

Rare diseases Can look at different potential exposures at once Cheap and quick

Question 29

How is the error factor minimised in case-control studies?

Answer 29

Use 5x the number of controls than there are cases | Easier to find disease free individuals

Question 30

Which types of bias are case-control studies heavily affected by?

Answer 30

Selective - individuals chosen not representative of general population eg a rare heat condition, people chosen from the same ward Recall - exposure status incorrectly determined due to looking back in history to determine exposure status

Question 31

How are confounding factors limited in case controls?

Answer 31

Matching up cases and controls with similar details

Question 32

What does an RTC involve?

Answer 32

Finding a source of eligible patients Ask them to participate Allocate patients to each treatment fairly Follow up participants in identical ways Minimise losses to follow up and maximise compliance Analyse data and obtain results

Question 33

What type of bias does double blinding remove?

Answer 33

Selection bias

Question 34

What is intention-to-treat analysis?

Answer 34

Includes patients who were not compliant with the drug to give a more realistic idea of how well the drug will do in clinical practise

Question 35

What is the Bradford-Hill criteria used for?

Answer 35

To determine whether causal-effect relationship has been established by removing confounders, bias and chance.

Question 36

List as many Bradford-Hill criteria as you can

Answer 36

``` Strength of association Specificity of association Consistency of association Temporal sequence Dose response Reversibility Biological plausibility Coherence of theory ```

Question 37

In an RCT, how can losses be minimised?

Answer 37

Honest with the patient about what is involved Follow up appointments at practical times No coercion or inducements

Question 38

How can compliance be maximised in an RCT?

Answer 38

Simplified instructions Patient can ask any questions Simple and accessible for the patient

Question 39

How can compliance be monitored?

Answer 39

Urine samples | Blood tests

Question 40

In an RCT, what is clinical equipoise?

Answer 40

Only put the patient on the trial if there is a good chance that the new drug will be more effective than the current one -not subjecting the patient to a known less effective drug

Question 41

Ethics to be considered in RCTs?

Answer 41

Clinical equipoise Patient consent Scientifically robust (pursuit of information for the good of the general population) Ethical recruitment (in a region where the drug will take affect) Voluntariness