Ethics and biostats Flashcards
type of study that measures disease prevalence
cross-sectional
type of study that measures the odds ratio
case control
study that measures relative risk
cohort
sensitivity equation
TP/(TP+FN) or A /A+C
specificity equation
TN /TN+FP or D/B+D
PPV equation
TP/TP +FP or A/A+B
NPV equation
TN/TN+FN or D/D+C
draw the double bell curve of sens/spec
TN/FN/FP/TP
What likelihood ratios are significant?
LR+ > 10 and LR - <0.1
LR + equation
sensitivity/1-spec or TP rate/FP rate
LR - equation
1-sens/spec or FN rate/TN rate
increased sensitivity does what to a predictive value
increase NPV
decreased specificity does what to a predictive value
decrease PPV
increased specificity does what to a predictive value
increase PPV
decreased sensitivity does what to a predictive value
decrease NPV
OR equation
a/b / c/d = ad/bc
RR equation
a/(a+b)/ c/(c+d)
RR = 1 means
no association
RR >1
increased risk
RR <1
decreased risk
difference in risk between exposed and unexposed groups
attributable risk
AR equation
a/ a+b - c/c+d
the difference in risk attributable to the intervention compared to the control
ARR
RRR equation
RRR = 1-RR
the proportion of risk reduction attributable to the intervention as compared to the control
RRR
ARR equation
c/c+d - a/a+b
NNT equation
1/ARR
NNH equation
1/AR
bias when study pop is from hospital and less healthy
berkson bias
pygmalion effect
self-fullfilling prophecy
estimate of the chances that an event occurs in the treatment arm of a trial v the non tx arm
hazard ratio
hazard ratio < 1
treatment arm had decreased event rate
hazard ratio > 1
treatment arm had increased event rate
when screening tests detect a disproportionate number of slowly progressive diseases but miss rapidly progressive ones, leading to overestimation of the benefit of the screen
length bias
type 1 error
false positive conclusion
type 2 error
false negative conclusion
power equation
= 1 - type 2 error
subunit vaccines
HBV, pertussis, s. pna, HPV, meningococcus
live attenuated vaccines
MMR, sabin polio, yellow fever, influenza nasal spray, varicella
inactivated vaccines
cholera, HAV, polio salk, rabies, influenza injection
toxoid vaccines
diphtheria, tetanus
conjugate vaccines
Hib, S. pna