HaDPop

Question 1

Define a census

Answer 1

Simultaneous recording of demographic data of all persons in a defined area

Question 2

What are some uses of a census?

Answer 2

Allocation of resources, population projections and seeing trends

Question 3

What is crude birth rate?

Answer 3

Live births per 1000 population

Question 4

What is gross fertility rate?

Answer 4

Live births per 1000 women aged 15-44

Question 5

What is total period fertility rate?

Answer 5

The average number of children born to a hypothetical woman in her lifetime (birth rate of each age bracket)

Question 6

What is crude death rate?

Answer 6

Number of deaths per 1000 population

Question 7

What is prevalence?

Answer 7

Amount of people who have the disease in a set population

Question 8

What is standardised mortality rate?

Answer 8

Mortality rate that takes into account confounding factors, mainly age and sex.

Question 9

How is standardised mortality rate worked out?

Answer 9

(observed deaths/expected deaths) x 100

Question 10

What is incidence rate?

Answer 10

Number of new cases of the disease per 1000 people per year

Question 11

How is incidence rate worked out?

Answer 11

New cases exposed/(population x years)

Question 12

What is an incidence rate ratio?

Answer 12

A comparison of the incidence rates of two populations with varying exposures

Question 13

How is incidence rate ratio worked out?

Answer 13

( New cases exposed/(population x years) ) / ( New cases unexposed/(population x years) )

Question 14

What is a confounding factor?

Answer 14

Factor associated with both outcome and exposure, but not causal

Question 15

What are confidence intervals?

Answer 15

A range of values in which we can be 95% confident that the true value lies within

Question 16

What is the relationship between the null hypothesis and confidence intervals?

Answer 16

If the 95% confidence interval contains zero (more precisely, the parameter value specified in the null hypothesis), then the effect will not be significant at the 0.05 level.

Question 17

What is selection bias?

Answer 17

Bias due to systematic difference in the way two groups are collected

Question 18

What is information bias?

Answer 18

Bias due to systematic misclassification of subjects in a group

Question 19

What is the healthy worker effect?

Answer 19

People at work are likely to be more healthy, or be exposed to certain things. They can’t be compared to reference population unless it is another working group.

Question 20

What does a cohort study involve?

Answer 20

Recruiting disease free individuals, classifying by exposure status, following up and calculating incidence rates

Question 21

What types of exposures is a cohort study good for studying?

Answer 21

Rare

Question 22

What is the difference between prospective and retrospective studies?

Answer 22

Prospective- disease free individuals, followed up after exposure

Retrospective- disease free individuals recruited and exposure status calculated from historical data

Question 23

What is the difference between internal and external comparisons, in cohort studies?

Answer 23

Internal- comparison between sub cohorts within larger cohort. Comparison of exposed and unexposed within cohort so IRR used

External- comparison with reference population. SMR used

Question 24

What does a case-control study involve?

Answer 24

Disease free controls and diseased cases recruited and odds ratio worked out to determine exposure status

Question 25

Can you work out odds ratio?

Answer 25

-

Question 26

Can you work out error factor?

Answer 26

-

Question 27

What does an odds ratio of 1 show?

Answer 27

Null hypothesis

Question 28

What is the benefit of having more controls?

Answer 28

Error factor size reduced

Question 29

How are confounders removed in a case-control study?

Answer 29

Matching

Question 30

What is the effect of randomisation?

Answer 30

Confounders removed

Question 31

Why is intention to treat analysis better?

Answer 31

More valid, as reflects how drug would be used

Question 32

What are the Bradford-Hill criteria and what do they determine?

Answer 32

Biological plausibility, strength of association, specificity of association, consistency of association, dose response, temporal sequence, coherence of theory. They determine causality

Question 33

How can compliance be measured?

Answer 33

Blood and urine testing

Question 34

What are some ethical considerations in undertaking a randomised control trial?

Answer 34

Is it good for population? Ethical recruitment, consent and clinical equipose

Question 35

What is a systematic review and meta-analysis?

Answer 35

Analysis of primary studies and quantitative synthesis of primary studies

Question 36

What is a funnel plot useful in showing?

Answer 36

Publication bias. A well balanced systematic review will have funnel shape

Question 37

What is publication bias?

Answer 37

Only using published studies (which are more likely to show statistical significance)

Question 38

What is the difference between the fixed effects model and the random effects model?

Answer 38

Fixed effects- assumes studies are homogenous and variation comes from within-study variation

Random effects- assumes studies are heterogenous and variation comes from within-study variation and between-study variation

Question 39

What are the advantages of systematic reviews?

Answer 39

Explicit methods, meta analysis gives overall figure, clinically useful and fits into evidence based practice