biostats Flashcards

1
Q

What is the definition of sensitivity?

A

Probability of a disease person testing positive

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2
Q

What is the formula for sensitivity?

A

TP/TP+FN

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3
Q

What is the definition of specificity?

A

Probability of a non diseases person testing negative

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4
Q

What is the formula for specificity?

A

TN/TN+FP

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5
Q

What is the definition for positive predictive value?

A

Probability that the disease is present when you have a positive result

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6
Q

What is the definition for negative predictive value?

A

Probability that the disease is absent when you have a negative result

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7
Q

What is the definition for positive likelihood ratio?

A

Likelihood of having a disease with a positive test result

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8
Q

What is the definition of negative likelihood ratio?

A

Likelihood of not having a disease with a negative test result

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9
Q

What is the formula for positive likelihood ratio?

A

sensitivity/ 1- specificity

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10
Q

What is the formula for negative likelihood ratio?

A

1-sensitivity/specificity

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11
Q

What is primary prevention?

A

Educating and screening a patient to prevent disease. Action taken before patient develops disease

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12
Q

What is secondary prevention?

A

Attempt to halting progression of disease

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13
Q

What type of study should you calculate odds ratio?

A

case control studies

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14
Q

What type of study should you calculate relative risk?

A

cohort study

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15
Q

What is the definition of relative risk?

A

Risk of developing disease in exposed group/ risk of developing disease in the unexposed group

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16
Q

What is the formula for relative risk?

A

(a/a+b)/(c/c+d)

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17
Q

What is the formula for NNT?

A

1/ARR

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18
Q

What is the formula of ARR?

A

(Events from controlled group) - (Events from treatment group)

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19
Q

What is the formula for ARP?

A

Risk in exposed- risk in unexposed or RR-1/RR

20
Q

What is the formula for PARP?

A

Risk in total population - Risk in unexposed/ Risk in total population

21
Q

What is the formula for RRR?

A

1- RR

22
Q

What is the purpose of intention to treat analysis?

A

Protects randomization

23
Q

What is length time bias?

A

When you have a highly aggressive disease that is not able to be picked up by screening test. (Picks up benign cases)

24
Q

What is lead time bias?

A

When a screening test picks up a disease earlier than it would have been diagnosed leading to the assumption the patient has survived longer

25
Q

What is sensitivity analysis?

A

repeating primary analysis calculation after modifying certain criteria or variables

26
Q

What is propensity scoring and matching?

A

Ensuring balance between variables in treatment and control groups

27
Q

What is the standardized mortality ratio (SMR)?

A

Observed # of deaths/ expected # of deaths

28
Q

What is the net clinical benefit of a study?

A

The benefits and harms of a study

29
Q

What is verification bias?

A

When a study uses a gold standard test selectively

30
Q

What is the purpose of funnel plots?

A

helps in assessing publication bias

31
Q

What is analysis of variance?

A

Means of several groups are being compared

32
Q

What is the fisher exact test?

A

Study association between 2 variables with a small sample size

33
Q

What is accuracy?

A

Looks at how close you come to the gold standard

34
Q

What is precision?

A

looks at how often you get the same readings

35
Q

What is type 1 error?

A

when you say there is a association when there is really no association

36
Q

What is type 2 error?

A

When you say there is no association when an association actually exist

37
Q

Alpha is what type of error?

A

type 1 error

38
Q

Beta is what type of error?

A

type 2

39
Q

What is the formula for power?

A

1- beta

40
Q

What is the standardized incidence ratio?

A

determines if the occurrence of cancer in a small population is high or low relative to an expected value derived from a larger comparison population

41
Q

What is the formula for standardized incidence ratio?

A

observed cases/expected cases

42
Q

Which tests are most appropriate for screening?

A

Highly sensitive test

43
Q

Which tests are most appropriate for confirmatory test?

A

Highly specific tests

44
Q

What are factorial study designs?

A

utilizes 2 or more interventions and all combinations of the interventions

45
Q

What can threaten the internal validity of a study?

A

cofounding

46
Q

What is the case fatality rate?

A

refers to the proportion of patient with a particular disease who die from the disease