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Flashcards in Behavioural Sciences Deck (78)
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What is a cross sectional study? What can it be used to measure?

Assesses frequence of disease (or other factors) in a group of people at a particular point in time - What is happening?

Measures disease prevalence - shows risk factor association with disease NOTE correlation =/= causation


What is a case control study? What does it measure?

Compares group with disease to control - Looks for risk factor

Measures Odds ratio


What is a cohort study? What does it measure?

Compares group with risk factor to group without risk factor. Looks to see if exposure increases likelihood of disease. Can be retrospective or prospective.

Measure relative risk - e.g. smokers had higher risk of developing COPD than non smokers.


What is a twin concordance study? What does it measure?

Compares the frequency with which both monozygotic twins or both dizyogtic twins develop the same disease;

Measures nature vs nurture



What is an adoption study? What does it measure?

Compares siblings raised by biological vs adoptive parents

Measures nature vs nurture


What does a triple blinded clinical trial entail?

Blinding of patients, doctors and researchers analyzing the data


What is the purpose of a phase I clinical trial?

Assesses safety, toxicity, pharmacokinetics and pharmacodynamics


What is the purpose of the phase 2 clinical trial?

Assesses treatment efficacy, optimal dosing and adverse effects


What is the purpose of phase 3 clinical trials?

Compares new treatment to current treatment or placebo


What is the purpose of phase 4 clinical trials? what does it involve?

Postmarketing surveillance of patients after treatment is approved. 

Detects rare or long term adverse efects


Define the sensitivity of a test.

Probability that a test detets a disease when disease is present.

SN-N-OUT = a highly SeNsitive test, when Negative, rules OUT disease


Define the specificity of a test

Probability that the test detects no disease when disease is absent.

SP-P-IN = a highly SPecific test, when Positive, rules IN disease


Define positive predictive value

Probability that a person actually has the disease when given a positive test result


Define negative predictive value

Probability that person actually is disease free when given a negative test result


Define incidence and prevalence

Incidence - no of new cases / no of people

Pevalnce = no of existing cases / no of people at risk


Define odds ratio

Odds tht the group with the disease was exposed to a risk factor divided by odds that the group without the disease was exposed


Define the relative risk

Risk of developing disease in exposed group divided by risk in unexposed group


Define the attributable risk

difference in risk between exposed and unexposed groups 


Define relative risk reduction

Proportion of risk reduction attributable to the intervention as compared to a control

RRR = 1 - Relative Risk


Define absolute risk reduction 

Difference in risk attributable to the intervention as compared to a control

ARR = (c/c+d) - (a/a+b)


Define the number needed to treat

Number of patients who need to be treated for 1 patient to benefit


Define the number needed to harm

number of patients who need to be exposed to a risk factor for 1 patient to be harmed


Define precision of a test

absence of random variation in test


Define the accuracy of a test

Trueness of test measurements


What is the berkson bias?

Study population selected from hospital is less healthy than general population


What is the healthy worker effect?

Study population is more healthy than general population


What is the non response bias?

participating subjects differ from nonrespondents in meaningful ways


How would you reduce selection bias?


Ensure the choice of the right comparison group


How would you reduce recall bias?

Decrease time from exposure to follow up


What is measurement bias and how would you reduce it?

Info is gathered in a way that distorts it

Reduced using a standardised method of data collection