Behaviorial Science/Biostats Flashcards
power of a study increases w/
increased sample size, expected effect size, precision management
power =
1 - beta
beta = stating there ISN’T an effect/difference when ONE EXISTS
sensitivity =
test detects dz when dz present; screening test (rule out a dz)
1 - FN rate
TP/(TP + FN) aka TP/total dz +
a/(a+c)
specificity =
test indicates NO DZ when dz actually absent; confirmatory test (rule in a dz)
1 - FP rate
TN/(TN+FP) aka TN/total dz negatives
d/(b+d)
PPV
person WITH dz tested positive in test
TRUE POSITIVE!!
TP/(TP+FP)
a/(a+b)
high pretest probability = high PPV
NPV
person WITHOUT dz who tested negative in test
TRUE NEGATIVE!!
TN/(FN+TN)
d/(c+d)
high pretest probability = LOW NPV
incidence
of new cases
prevalence
incidence x time
looks at ALL current cases –> tx that prolongs survival INCREASES prevalence
odds ratio (OR)
used in case-control studies
odds that group w/ dz exposed to risk factor divided by odds that group w/o dz exposed to risk factor = (a/c)/(b/d) =
ad/bc
relative risk (RR)
used in cohort studies
risk of developing dz in exposed group divided by risk in unexposed group
[a/(a+b)]/[c/(c+d)]
if low prevalence –> RR = OR
attributable risk
difference in risk b/w exposed/unexposed groups
Attributable Risk % = (RR - 1)/RR
[a/(a+b)] - [c/(c+d)]
event rate(of tx) - event rate(in other group)
Absolute risk reduction (ARR)
AR(in control) - AR(w/ tx)
[c/(c+d)] - [a/(a+b)]
needed to treat
pts needed to treat for 1 pt to benefit
1/ARR
needed to harm
of pts who need to be exposed to RF for 1 pt to be harmed
1/attributable risk
relative risk reduction (RRR)
[AR(control) - AR(tx)]/AR(control)
type 1 error (alpha)
stating there IS an effect when there ACTUALLY IS NOT (mistakenly reject null hypothesis)
b/(b+d)
type II error (beta)
stating there IS NOT an effect when there ACTUALLY IS (fail to reject null hypothesis)
c/(a+c)
95% confidence interval Z-score =
1.96
99% confidence interval Z-score =
2.58
standard error of mean (SEM) =
SD/(sq rt of n)
SD (standard deviation) = aka sigma
n = sample size
formula to obtain confidence limits
mean +/- [Z-score x SEM]
wave seen in awake stage?
beta (highest freq, lowest amp)
wave seen in relaxation stage?
alpha
wave seen in N1 stage?
theta
wave seen in N2 stage?
sleep spindles and K complexes
wave seen in N3 stage?
delta (lowest freqm highest amp)
wave seen in REM?
beta
what stage of sleep does night terrors, bedwetting, sleep walking occur
N3 - NO memory of sleep terror (as opposed to REM)
REM occurs due to what part of brain
PPRF (paramedian pontine reticular formation)
REM stage ass w/?
dreaming
loss of motor tone
erections
increased brain O2 use
sleep stage w/ bruxism (teeth grinding)
N2
sleep enuresis preferred tx
DDVAP (oral desmopressin acetate)
preferred over imipramine, indomethacin
key NT changes in REM sleep
increased ACh
NE reduces REM sleep
primary sleep stage in narcolepsy
straight to REM sleep
tx for narcolepsy
modafinil, amphetamines (stimulants) sodium oxybate (GHB) - for nighttime
NT change in narcolepsy
decreased hypocretin-1 from lateral hypothalamus
