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1 Population and Social Science > Population and Social Science > Flashcards

Population and Social Science Flashcards

1
Q

Name the 4 types of observational studies.

A
  • Descriptive
    • Cross-sectional
    • Ecological
  • Analytical
    • Case-control
    • Cohort
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2
Q

Describe how an ecological study is conducted.

A
  • Population level (group analysis)
  • Observational
  • Ecological fallacy (inference made about individuals from group data collected)

(Ecological fallacy= type of confounding variable)

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3
Q

Describe a cross-sectional survey/study.

A
  • Measures exosure and disease- one point in time
  • Data from individuals
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4
Q

Define prevalence and incidence rate.

A

Prevalence: Existing cases as proportion of population

Incidence rate: New cases in population per year (Person-years)

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5
Q

What can prevalence and incidence rate be used to measure?

A

Absolute risk (of event happening)

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6
Q

What is an incidence rate ratio?

A

Compares incidence rate of 2 populations

Is exposure associated with condition?

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7
Q

What is the difference between incidence rate ratio and risk ratio?

A

Incidence rate ratio= incidence rate

Risk ratio= prevalence

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8
Q

Identify a solution to limit the effect of confounding variables in a study.

A
  1. Selection (match confounders)
  2. Calculations (standardisation, stratifying etc)
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9
Q

What is the standardised mortality ratio?

A

SMR: Observed/expected deaths x 100

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10
Q

What does a SMR> 100 suggest?

A

Excess mortality with confounders accounted for

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11
Q

When measuring mortality rate, what’s the difference between direct and indirect standardisation?

A

Direct= uses reference population (same population numbers)

Indirect= uses mortality rates from one population to another (observed and expected deaths)

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12
Q

What is the sampling frame?

A

List or method through which sample= obtained

(assumed to be representative of population)

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13
Q

Why do we use an Error Factor (EF) with epedimiological studies?

A
  • True value of population= different to sample
  • Error factor used to help infer true value
  • Size of EF depends on size of population
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14
Q

What is the confidence interval?

(Use EF to work out CI)

A

Interval where the true value lies

(which we can say with 95% confidence)

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15
Q

What are the 2 types of validity a study must have?

A
  1. Internal validity
    1. Freedom from confounding, bias, random error
  2. External validity
    1. Degree to which conclusions from study can be applied to population of interest
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16
Q

Define bias.

A

Systematic error….

…measuring exposure/ covariates/outcome variables…

…leads to erroneous association

17
Q

What are the 2 main types of bias?

A
  • Selection bias
  • Information bias
18
Q

What is selection bias?

A

Selected sample not representative of patient population

19
Q

Why might selection bias occur?

A
  • Systematic error selecting subjects
  • Factors influencing participation
20
Q

How might information bias occur?

A
  • Misclassification of participants
  • Recall error/bias (case-control problem)
  • Observer error/bias
  • Measurement error/bias
21
Q

Describe how a cohort study is conducted?

A
  1. Recruit disease-free individuals
  2. Classify according to exposure
  3. Follow - long periods of time
  4. Monitor disease progress
  5. Calculate incidence rates

Retrospective/prospective

22
Q

What are the advantages of cohort studies?

A

Good for:

  • rare exposures (not good for rare outcomes)
  • conditions fluctuating with age
  • multiple outcomes
  • showing exposure precedes outcomw
23
Q

What are the disadvantages of cohort studies?

A
  • Resource intensive
  • Take long time
  • Survivor bias
  • Difficult with unknown confounders
24
Q

How are case-control studies carried out?

A
  • Recruit disease free and diseased individuals
  • Determine exposure status of each group
  • Produce odds ratio (measure of relative risk)
25
Q

How are controls found for case-control studies?

A

Found to match confounders eg age, sex

Make 2 populations as similar as possible

26
Q

What can be done when conducting a case-control study to minimise the EF (error factor)?

A

Use more controls than cases

27
Q

Give some advantages of using a case-control study:

A
  • Good- rare disease
  • Cheap
  • Quick
  • Can study multiple exposure for single outcome
28
Q

Give some disadvantages of using a case-control study:

A
  • Prone to selection and information bias
  • Not good for rare exposures
  • Confounding
29
Q

Looking at the following table, how is the odds ratio calculated?

A
30
Q

Differentiate between cohort and case-control studies.

A
31
Q

What is the Bradford-Hill criteria and what is it used for?

A
  • Assesses how sure we are of a causal relationship
  • Criteria:
    • Association
    • Exposure&Outcome
    • Other evidence
32
Q

Why are RCTs (randomised controlled trials) carried out?

A

To assess:

  • Efficacy (benefit of treatment under specified conditions)
  • Safety (not doing harm under specified conditions)
33
Q

RCTs(randomised controlled trials) must be reproducible (under same conditions). They must also be 2 other things- what are these?

A
  1. Controlled
    1. Comparison of intervention
  2. Fair
    1. Unbiased, no confoundin/g
34
Q

What 3 measures can be taken to ensure that randomised control trials (RCTs) are reproducible, controlled and fair?

A
  1. Randomisation
    1. Removes confounding and allocation bias
  2. Blinding
    1. Removes measurement bias and non-treatment effects
  3. Placebo
    1. (patients must be told if standard treatment available)

1 Population and Social Science (2 decks)

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