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J Term 2 mix > Hadpop2 > Flashcards

Hadpop2 Flashcards

1
Q

What is a census

A

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

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2
Q

What is a census useful for

A
  1. allocation of resources
  2. trends in populations, eg ethnicity
  3. projections of populations (how many people living in this area with this defined problem)
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3
Q

3 ways to measure Birth rates

A
  1. Crude BR: # of live births per 1000 population
  2. General fertility rate: # of live births per 1000 fertile women between 15-44 - more accurate but not always possible
  3. Total period fertility rate: average # of children born to a hypothetical woman in her lifetime
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4
Q

How can death rates be measured

A
  1. Crude mortality rate

2. age-specific mortality rate

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5
Q

Define incidence

A

Number of new cases per year in a set population, per 1000 people/per year

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6
Q

Define prevalence

A

Number of people with the disease in a set population

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7
Q

What is SMR

A

Standardized Mortality Rate
calculated by: observed # of deaths x 100/expected # of deaths

SMR>100 suggests excess mortality and <100 suggests less mortality with confounders accounted for

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8
Q

What is the p-value

A

indicates the percentage of the study due to chance, based around 5%

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9
Q

State 3 types of selection bias

A
  • allocating
  • healthy worker effect
  • non-response bias
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10
Q

State 4 types of information bias

A
  • instrument
  • interviewer
  • recall bias
  • publication bias
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11
Q

Define a cohort study

A

Recruiting disease-free individuals and following up with them for an extended period of time, and classify them according to their exposure status

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12
Q

State 2 types of cohort studies, and define each one

A
  1. Prospective: disease-free individuals recruited and followed up
  2. Retrospective: choosing disease-free individuals based on a common past exposure and following up
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13
Q

What’s an internal comparison

A

Occurs when you have sub-cohorts within your original group and compare the exposed to the unexposed

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14
Q

What’s an external comparison

A

Comparing your exposed group to a reference population

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15
Q

What is the only study design that allows you to calculate odds ratio?

How would you do it?

A

Case-control studies
Case: diseased individuals, control: disease-free individuals. Want them as similar as possible

a: exposed cases
b: exposed controls (disease-free individuals)
c: unexposed cases
d: unexposed controls

a/c over b/d
A crazy big dick:)

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16
Q

List 4 advantages for Case-Control

A
  1. used for rare diseases
  2. temporal sequencing
  3. can look at multiple exposures at once
  4. Fast and inexpensive (relatively)
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17
Q

Define temporal sequencing

A

Confidently say that exposure came before the outcome

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18
Q

What is intention to treat

A

Treating everyone the same regardless if they are given the real drug or placebo in an RCT

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19
Q

Why is it important to keep non-compliars in a study

A

If non-compliars (those non-compliant) with the drug are removed, loss of randomization also occurs from the trial

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20
Q

What is the purpose of the Bradford Hill Criteria

A

To determine whether the causal-effect relationship has been established
Can you directly say this exposure caused the outcome?

21
Q

List the 9 Bradford Hill Criteria

A

STD-C-CRABS
Strength of association: stronger the association between exposure and outcome, less likely due to chance, confounding or bias

Temporal sequencing

Dose-response: does the outcome change with increasing/decreasing dosage

Consistency of association; does same association occur in other studies

Coherence of Theory: does the observed observation confirm your scientific thinking

Reversibility: if you remove the causal factor, would you get a reduced risk of the outcome

Analogy: does a similar disease have similar outcomes

Biological Plausibility: is there a plausible biological mechanism to support the theory

Specificity of association: the outcome is associated with a specific factor

22
Q

Three ways losses can be minimized by, aka three ways to minimize loss to follow up

A
  1. Follow up appointments
  2. No coercion or inducements
  3. Honesty
23
Q

What is loss to follow up and when is it significant?

A

When a patient stops participating in the study before its completion.

A weakness of RCTs and cohort studies, since your results depend on the future results, so you don’t want your patients to drop out of the study

24
Q

Three ways to maximize compliance of patients

A
  1. Simplified instructions
  2. Patient allowed to ask lots of questions
  3. Made simple and accessible for patient
25
Q

How and when would you calculate RR

A

For RCTs:
risk of exposed with disease/total = x

risk of unexposed with disease/total = y

x/y= “Value”, Risk of the exposed getting the disease is “Value” times as likely as a nonexposed individual.

26
Q

List the 4 pillars of medicine

A

Principle of…

  1. Beneficence (do good)
  2. Non-maleficence (do no harm)
  3. Autonomy (let the patient decide)
  4. Justice (be fair)
27
Q

What is a systemative review?

A

Compilation of all primary studies (many RCTS), you narrow them down the most relevant and credible

28
Q

List 3 characteristics that a study used in a systemative review should have

A
  1. Transparency - nothing hidden
  2. Reproducible - can you reproduce the exact same study again
  3. Explicit - clear
29
Q

What’s a meta-analysis and when is it used

A

Within a systemative review that provides an overall value with associated CI.

Used in a forest plot

30
Q

In a forest plot, what does…

a) The square represents
b) the horizontal lines
c) the size of the square
d) the diamond
e) solid vertical line

A

a) The odds ratio value
b) the CI
c) the amount of weight on the study
d) The pooled estimate: the average of the studies, the width of the diamond represents the overall 95% CI
e) The Null Hypothesis

31
Q

List the two types of models that can be used in a meta-analysis

A
  1. Fixed effects model - assumes the studies used are homogenous, they’re so similar that any variation between data comes from within the study
  2. Random effects model - assumes studies are heterogeneous and variation between data comes from in the study and between separate studies
32
Q

What is a funnel plot

A

Publication bias can be determined using a funnel plot…

Publication Bias: whereby studies are only likely to be published if results are statistically significant or have a large sample size

The more funnel-shaped, the less publication bias

33
Q

List 3 advantages of RCTs

A
  1. You can introduce blinding
  2. eliminates confounders
  3. you can actually test the intervention
34
Q

How is Prevalence calculated

A

of cases at a given time/population # at the time

35
Q

How is Cumulative Incidence calculated and expressed in units, and what does the value mean?

A

of new cases of a disease in a period of time/# of people at risk of developing the disease at the start of the same time period

As a percentage

How many people at risk actually got the disease

36
Q

How would you calculate Incidence Density and what does that value show?

A

of new cases of a disease/Total person-time at risk of developing the disease

Shows how many people who were at risk for x amount of time actually got the disease

37
Q

List the general steps for a Cohort study

A
  1. recruit a population of disease-free individuals
  2. classify them based on their exposure status, e.g; How many of them have had the BCG
  3. Follow up with them for an extended period of time
38
Q

What does Internal Validity measure

A

Are the finding of the study valid for the population in the study

39
Q

What does external validity measure

A

can the findings be generalizable to other populations outside of the study?

40
Q

3 advantages for a cohort study

A
  1. temporal sequencing
  2. can examine multiple outcomes (the final results) from one exposure
  3. Good for rare exposures (but bad for rare outcomes)
41
Q

What three disadvantages do RCTs and cohort studies have in common

A
  1. Time
  2. Expensive
  3. risk of loss to follow up
42
Q

List two disadvantages for a case-control

A
  1. Difficult to select the appropriate control groups as you want them to be as characteristically similar to the case group, (asides from lack of exposure)
    e. g; similar age, gender, height, etc.
43
Q

Define a confounding factor and list 5 examples

A

Is independently associated with the exposure and the outcome but is not on the causal pathway

age, gender, genetics, height, smoking (when it’s not the exposure being examined)

44
Q

If a CI value includes the null Hypothesis it is…

A

Not statistically significant, therefore we accept the Null Hypothesis

45
Q

If a CI value doesn’t include the null hypothesis it is…

A

statistically significant, therefore we accept the alternate hypothesis

46
Q

What’s a case series?

A

The absolute fcking worst type of study design, based on reports

47
Q

What does the incidence rate ratio show

A

It compares the incidence rates between groups with different levels of exposure

48
Q

What does the relative risk show

A

Compares cumulative incidence (a proportion) between groups with different levels of exposure

49
Q

List in order from top –> bottom the study design triangle

A
  1. Systemative review
  2. RCT
  3. Cohort studies
  4. Case control
  5. Cross sectional
  6. Case series

J Term 2 mix (8 decks)

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