Biostats/Epi. Flashcards
Cross-sectional study measures….
Disease prevalence
Case-control study measures…
Odds ratio (OR)
Cohort study measures….
Relative risk (RR)
Prevalence of diseases with short duration =
roughly the incidence rate
OR =
(A/C) / (B/D)
RR =
[a/(a+b)] / [c/(c+d)]
AR =
a/a+b - c/c+d
RRR =
1 - RR
ARR -
c/c+d - a/a+b
NNT =
1/ARR
NNH =
1/AR
Attributable risk % in the exposed =
100 x (RR-1)/RR
Increased precision…
Increased statistical power
berkson bias
study pop selected from hospital is less healthy than general pop
Pygmalion effect
Researchers belief in efficacy of Tx changes the outcome
Hawthorne effect
subjects change behavior when they know they are being observed (observer effect)
SEM (standard error of the mean) =
SD/square root of n (SEM decreases w/ increased sample size
Increased power by:
increasing sample size, expected effect size, precision of measurement
For the 95% CI, Z = For the 99% CI, Z =
1.96 2.58
CI =
mean +/- Z x SEM
Sensitivity =
1 - false negative rate
Specificity =
1 - false positive rate
Errrors
Coeffecient of determination
R2
Medicare
Patients above 64
Under 65 with certain disabilites
Those with end-stage renal disease
Medicaid
Joint federal and state program for people with very low income
Medicare parts
A - hospital insurAnce
B - Basic medical Bils
C - (Parts A+B) delivered by approved private Companies
D - Prescription Drugs
