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

Question 1

as prevalance decreases sensitivity and specificity what

Answer 1

remain unchanged

Question 2

as prevelance decreases, NPV ____ and PPV ___

Answer 2

NPV increases

PPV decreases

PPV and prevealance are inversely related

Question 3

sensitivity equation

Answer 3

A/ A+C

Question 4

specificity equation

Answer 4

D/ B+D

Question 5

positive predictive value equation

Answer 5

A / A +B

Question 6

negative predicvitve value equation

Answer 6

D / D +C

Question 7

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

Answer 7

increases FP
decreases FN

lower sPecificity, lower PPV
higher seNsitivity, higher NPV

Question 8

raising the upper limit for being a postivie screen does what

Answer 8

increases the FN
decreases the FP

increases sPecificity
increases PPV

decreases seNsititivy
decreases NPV

Question 9

high _____ test used for screening in disesae with low prevalance

Answer 9

sensitivity

Question 10

increased prevalence does what to specificity and sensitivity

Answer 10

nothing

same with decreased prevelance

Question 11

relative risk is used in what studies

Answer 11

cohort

Question 12

equation relative risk

Answer 12

a/a+b / c/c+d

Question 13

relative risk reduction equation

Answer 13

1 -RR

Question 14

if prevelance is low then OR

Answer 14

= RR

Question 15

berkson bias

Answer 15

study pop selected from hosptial is less healthy than general pop

Question 16

healthy worker effect

Answer 16

study pop is healthier than the gen pop

Question 17

non response bias

Answer 17

participating subjects differ from nonrespondents in meaningful ways

Question 18

3 types of selection bias

Answer 18

berkson, healthy worker, non response

Question 19

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

Answer 19

measurement bias

Question 20

subjects in different groups are not reateed the same

Answer 20

procedure bias

Question 21

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

Answer 21

obserrver expectancy bias

Question 22

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

Answer 22

lead time bias

Question 23

positive skew

Answer 23

mean > median > mode

Question 24

negative skew

Answer 24

mean < median < mode

Question 25

false positive error

Answer 25

type I error B in 4 x 4

Question 26

false negative error

Answer 26

type II error C in 4 x 4

Question 27

consent for minors

Answer 27

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

Question 28

situations in which parental consent is usually not req

Answer 28

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