Behavioral Science Flashcards
Sensitivity equation?
TP/(TP+FN)
Specificity equation?
TN/(TN+FP)
PPV equation?
TP/(TP+FP)
NPV equation?
TN/(TN+FN)
Incidence rate?
new cases/# ppl at risk
Prevalance?
of existing cases/total # in population
Odds rato
(a/c)/(b/d)=ad/bc or (a/b)/(c/d)
Relative risk
(a/(a+b)/(c/(c+d))
Attributable risk
AR=(a/a+b)-(c/c+d)
Relative risk reduction
RRR=1-RR
Absolute risk reduction
c/c+d-(a/a+b)
Number needed to treat
NNT=1/ARR
Number needed to harm
NNH=1/AR
Risk (probability of developing a disease over a certain period of time)
(a/a+b)
Standard deviation vs Standard error in terms of description
Standard deviation-how much variability exists from the mean in a set of values
Standard error-variance in mean between the sample and the true population mean
When does mean=median=mode?
only in a normal distribution
Error in assigning subjects to a study group resulting in an unrepresentative sample
Selection bias
Awareness of disorder alters recall by subjects; common in retrospective studies
Recall bias
Information is gathered in a way that distorts it
Measurement bias
Subjects in different groups are not treated the same
Procedure bias
Researcher’s belief in the efficacy of a treatment changes the outcome of that treatment
Pygmalion effect seen in observer expectancy bias
Sending survey out to patients 5 years after diagnosis is preferentially sampling those with low grade disease
Late-look bias
When a factor is related to both the exposure and outcome, but not the causal pathway–> factor distorts or confuses effect of exposure on outcome
Confounding bias
Present when the effect of the main exposure on the outcome is modified by the presence of another variable. It is a natural phenomenon that should be described, but not connected
Effect modification