biostats (i dont understand any of this just memorize random equations and pray) Flashcards

1
Q

as prevalance decreases sensitivity and specificity what

A

remain unchanged

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2
Q

as prevelance decreases, NPV ____ and PPV ___

A

NPV increases

PPV decreases

PPV and prevealance are inversely related

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3
Q

sensitivity equation

A

A/ A+C

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4
Q

specificity equation

A

D/ B+D

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5
Q

positive predictive value equation

A

A / A +B

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6
Q

negative predicvitve value equation

A

D / D +C

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7
Q

lowering a tests upper limit for being a positive screen does what

A

increases FP
decreases FN

lower sPecificity, lower PPV
higher seNsitivity, higher NPV

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8
Q

raising the upper limit for being a postivie screen does what

A

increases the FN
decreases the FP

increases sPecificity
increases PPV

decreases seNsititivy
decreases NPV

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9
Q

high _____ test used for screening in disesae with low prevalance

A

sensitivity

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10
Q

increased prevalence does what to specificity and sensitivity

A

nothing

same with decreased prevelance

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11
Q

relative risk is used in what studies

A

cohort

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12
Q

equation relative risk

A

a/a+b / c/c+d

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13
Q

relative risk reduction equation

A

1 -RR

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14
Q

if prevelance is low then OR

A

= RR

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15
Q

berkson bias

A

study pop selected from hosptial is less healthy than general pop

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16
Q

healthy worker effect

A

study pop is healthier than the gen pop

17
Q

non response bias

A

participating subjects differ from nonrespondents in meaningful ways

18
Q

3 types of selection bias

A

berkson, healthy worker, non response

19
Q

one survery teams hemoglobin machine malfunctioned and was not checked. so everyones Hb was the same when taken

A

measurement bias

20
Q

subjects in different groups are not reateed the same

A

procedure bias

21
Q

if observer expects treatment group to show signs of recovery, then he is more likely to document positive outcomes

A

obserrver expectancy bias

22
Q

early detection makes it seem as though survival has increased, but natural hisotry of disease has not changed

A

lead time bias

23
Q

positive skew

A

mean > median > mode

24
Q

negative skew

A

mean < median < mode

25
Q

false positive error

A

type I error B in 4 x 4

26
Q

false negative error

A

type II error C in 4 x 4

27
Q

consent for minors

A

in general, parental consent should be obtained unless emergent treatment is req or if minor is legally emancipated

28
Q

situations in which parental consent is usually not req

A

sex (contraception, STI, preg)
drugs (substance abuse)
rock and roll (emrgency/trauma)