First Aid Flashcards
Odds ratio calculation
For case control studies. Odds that group with dz was exposed to risk factor (a/c) divided by odds that group w/o disease (controls) was exposed (b/d)
Relative risk calculation
Used in cohort studies. Risk of developing dz in exposed group / risk in unexposed group
RR = a / (a+ b) / c/ (c+d)
If prevalence low, RR about equals OR.
Measurement bias
info is gathered in a way that distorts it, eg Hawthorne effect- groups who know they’re being studied behave differently than they would otherwise.
Better to blind.
Procedure bias
Subjects in different groups not treated the same. Eg pts in tx group spend more time in highly specialized hospital units.
Observer-expectancy bias
Researcher’s belief in efficacy of treatment challenges the outcome of that treatment (aka Pygmalion effect- self fulfulling prophecy). If observer expects tx group to show signs of recovery, more likely to document positive outcomes.
Confounding bias
When factor related to both exposure and outcome, but not on causal pathway–> factor distorts or confuses effect of exposure on outcome.
To reduce: Matching cases/controls based on similar characteristics, crossover studies, multiple studies
Lead time bias
To reduce: measure “back end survival” - adjust survival according to severity of dz at time of dx
Effect modification
Effect of main exposure on outcome is modified by another variable. Not a bias. Described, not corrected.
Effect is REAL but magnitude is different for different groups (eg blacks/whites, M/F)
Standard error of the mean
Estimation of how much variability exists between sample mean and true population mean. measure of the quality of the sample.
SEM = std dev / square root of N.
Positive skew
Means TAIL Is on positive side (right). So mean > median > mode
(negative skew is reverse)
Confidence interval
Range of values in which specified probability of means of repeated samples would be expected to fall. (interval in which true population mean lies)
CI = range from (mean - ZSEM) to (mean + ZSEM)
95% CI (p= 0.05) often used. Z = 1.96 (roughly 2)
99% CI–> Z= 2.58
99.7% CI –> Z = 3 (3 standard deviations)
Z score–> difference between individual variable and population mean in units of STD dev.
Surrogate decision making order
Spouse, adult children, parents, adult siblings, other relatives
Tarasoff decision
CA supreme court decision requiring physician to directly inform and protect potential victim from harm.
Apgar score
Appearance, Pulse, Grimace (reflex irritability), Activity (muscle tone), Respiration
> 7 = good. 4-6: assist and stimulate. <4: resuscitate.
Developmental milestones: 0-12 months
Parents Start Observing
Motor:
-Primitive reflexes disappear - moro by 3 mos, rooting by 4, palmar by 6, babinski by 12.
-Posture- lifts head up by 1 mo, sits by 6, crawls by 8, stands by 10, walks by 12-18.
-Picks: passes toys hand to hand (by 6 mo), Pincer grasp (10 mos)
-Points to objects (12 mo)
Social: Social Smile (2 mo), Stranger anxiety (6 mo), Separation anxiety (9 mo)
Verbal:
Orients (to voice by 4 mo, to name/gestures by 9)
-Object permanence (9 mos)
Oratory (mama by 10 mo)
