MHS

Question 1

What are the three types of Systematic Error or Bias in clinical trials? And what is it minimised by?

Answer 1

Selection bias (selection, loss to follow up)
Information bias e.g. recall bias
Reporting bias e.g. publication bias
Minimised by study design, blinding and randomisation

Question 2

What is a confounding error and what is it minimised by?

Answer 2

Known or unknown third factors associated with relationship under investigation
Minimsed by randomisation

Question 3

What two types of random error are there?

Answer 3

Type 1 (alpha) or Type 2 (beta)

Question 4

What is a type 1/alpha error? What is it controlled by?

Answer 4

False +ves

Level of significance

Question 5

What is a type 2/beta error? What is it controlled by?

Answer 5

False -ves

Large sample sizes

Question 6

What are the 3 main models of stress?

Answer 6

Stimulus, Response and Transactional

Question 7

What are the 3 phases of stress?

Answer 7

Phase 1 - Alarm
Phase 2 - Resistance
Phase 3 - Exhaustion

Question 8

What are the 2 sympathetic pathways (stress lectures)

Answer 8

SAM - sympathoadrenomedullary axis

HPA - hypothalamic pituitary adrenal axis

Question 9

Where is serotonin made?

Answer 9

Raphe nucleus

Question 10

Where is noradrenaline made?

Answer 10

locus coerulus

Question 11

What are the 5 main categories of stressors?

Answer 11

Life events, internal stressors, physical, lifestyle and environmental

Question 12

What is the choice principle?

Answer 12

That we should seek out events that are pleasurable and avoid those that are harmful or threatening

Question 13

What is the yerkeses- dodson principle

Answer 13

Performance increases with mental and physiological arousal but only up to a point
Too high performance decreases and there is tension and anxiety

Question 14

What is eustress?

Answer 14

Positive cognitive responses to stress e.g. athletic competition

Question 15

What was the study by Seligman and Maier (1967) looking at?

Answer 15

Learned helplessness

Question 16

What was the crowded train study?

Answer 16

Lundgberg 1976 - those who had been on the train from beginning were less stressed - were in control e.g. of finding and choosing where to seat

Question 17

What study in 1976 also showed that giving people a sense of personal control increased health?

Answer 17

Langer and Rodin

Question 18

What are the three types of decisions that have to be made?

Answer 18

Approach-approach
Avoidance - Avoidance
Approach - avoidance

Question 19

What is the purpose of randomisation in RCT’s

Answer 19

to ensure potential confounders (known and unknown) are balanced between intervention and control group

Question 20

What are the top 3 observational studies (in order)

Answer 20

Cohort studies
Case control studies
Self controlled case series

Question 21

What is an experimental study?

Answer 21

Studies in which exposure is determined as part of the study design

Question 22

What is an observational study?

Answer 22

Studies in which exposure is not determined as part of the study design. So already existing exposures and their consequences are studied

Question 23

What is a null hypothesis?

Answer 23

The hypothesis being tested imagining there are no links between either factor being investigated

Question 24

What is an alternative hypothesis?

Answer 24

What is believed to be true if the null hypothesis is false

Question 25

What is the p value?

Answer 25

The probability of seeing a difference of size by chance | Smaller p value is more likely to be real result

Question 26

What does it mean if p=0.05

Answer 26

That 5% or 1/20 chance of seeing a difference of the size observed as a result of chance

Question 27

What p value is said to be a statistically significant difference?

Answer 27

p<0.05 | 0.5 or above the null hypothesis is rejected and alternative accepted

Question 28

What is a case control study?

Answer 28

A study where subjects are chosen on the basis of whether or not they have the disease or health related state - retrospective Identification of exposure in the past

Question 29

What is a cohort study?

Answer 29

A study where the subjects are chosen on the basis of whether they are exposed or not - prospective Recruitment of cases as they happen

Question 30

What does the WHO define health as?

Answer 30

A state of complete physical, mental and social well-being and not merely the absence of disease of infirmity

Question 31

What is health inequality?

Answer 31

difference in health status of individuals and groups

Question 32

What is health inequity?

Answer 32

unfair differences in health status that are potentially avoidable

Question 33

What does the marmot review describe?

Answer 33

proportionate universalism - how disadvantage starts before birth and accumulates throughout life

Question 34

What are epidemic models?

Answer 34

Sets of equations that describe the rate of change of numbers infected

Question 35

How do we "deal" with chance associations?

Answer 35

By statistics and defining a probability level that we find acceptable - the alpha level

Question 36

What is the accepted alpha level?

Answer 36

1/20 i.e p<0.05

Question 37

How do you deal with confounding variables in a study?

Answer 37

Study design: to restrict the study to one stratum of the confounder or match for potential confounders Analysis: stratified analysis after having collected data on confounders

Question 38

What are residual confounding factors?

Answer 38

When all known confounders have been accounted for but there are other unknown confounders that are exaggerating or marking a true relationship

Question 39

What is the best way to deal with both known and unknown confounders?

Answer 39

randomisation

Question 40

What is incidence?

Answer 40

New events within a time dimension

Question 41

What is prevalence?

Answer 41

existing cases within a time

Question 42

What is point prevalence?

Answer 42

existing cases a specific time

Question 43

What is period prevalence?

Answer 43

existing cases over a time course

Question 44

What is cumulative incidence?

Answer 44

new cases over a time period but each with a different length of follow up

Question 45

What is standardisation?

Answer 45

Set of techniques used to remove as much as possible the effects of differences in confounders when comparing two or more populations

Question 46

What is indirect standardisation?

Answer 46

When from the reference population to find stratum specific rates and you apply these to the study population the generate the expect value --> then compare expected number of deaths with observed

Question 47

What is direct standardisation?

Answer 47

When from the study population to derive stratum specific rates and apply these to the reference population and derive the expected rate

Question 48

What is sensitivity?

Answer 48

The probability that a test on a patient with the condition will give a positive result = True positive = true positive/total with condition

Question 49

What is specificity?

Answer 49

The probability that a test on a patient without the condition will give a negative result = true negative = true negative/ total without the condition

Question 50

What is the positive predictive value?

Answer 50

The proportion of patients with positive test results that actually have the disease = true positive/ total positive

Question 51

What is the negative predictive value?

Answer 51

The proportion of patients with negative test results that don't have the disease true negative/total negative

Question 52

How do you calculate attributable risk?

Answer 52

Difference between absolute risk for control and treatment groups

Question 53

How do you calculate absolute risk?

Answer 53

no of events/ total no of people

Question 54

How do you calculate relative risk?

Answer 54

Absolute risk of treatment group / absolute risk of control group

Question 55

What is a de facto census?

Answer 55

People are enummerated according to where they stay on census night

Question 56

What is a de juro census?

Answer 56

People are ennumerated according to where they usually live