Behavioral Science Flashcards
(42 cards)
Odd Case
observational and retrospective
Compares a group of people with disease to a
group without disease.
Looks for prior exposure or risk factor.
Asks, “What happened?”
Odds ratio-ad/bc
Relative Cohort
a group of people that all have something in common. no one has disease of interest
Compares a group with a given exposure or risk
factor to a group without such exposure.
Looks to see if exposure t the likelihood of
disease.
Can be prospective (asks, “Who will
develop disease?”) or retrospective (asks,
“Who developed the disease [exposed vs.
non exposed]?”).
Relative risk=a/(a+b)//c/(c+d)
Cross sectional
prevalence study
Disease prevelance. Snap shot of population at a given time.
Collects data from a group of people to assess
frequency of disease (and related risk factors)
at a particular point in time.
Asks, “What is happening?”
Can show risk factor association with disease, but
does not establish causality.
Clinical trial
I-is it safe (sm number of healthy pts)
II-does it work (sm # of pts with disease)
III-does it work better (comparison) large population
IV-rare or long term adverse effects
Cross over study
subjects are randomly allocated to a sequence of 2 or more tx given consecutively. Pts serve as their own controls. Drawback of crossover trials is that the effects of tx 1 may carry over and alter the response of the subsequent tx. A “washout” period helps with this.
limits confounding bias
Sensitivity
Used for screening test with low prevalence.
=1-FN rate
SNOUT= Sensitivity rules OUT
Specificity
Used for confirmatory test after a positive screening test.
=1-FP
SPIN=specificity rules IN
PPV
PPV varies directly with prevalence or pretest
probability: high pretest probability–>high PPV
NPV
NPV varies inversely with prevalence or pretest
probability: high pretest probability–>low NPV
Attributable risk
The difference in risk between exposed and
unexposed groups, or the proportion of
disease occurrences that are attributable to the
exposure
a/(a+b)–c/(c+d)
Number needed to tx
Number of patients who need to be treated for 1
patient to benefit. Calculated as 1/absolute risk
reduction.
Absolute risk reduction
c/(c+d)–a/(a+b)
Absolute reduction in risk associated with a
treatment as compared to a control
Number needed to harm
Number of patients who need to be exposed
to a risk factor for 1 patient to be harmed.
Calculated as 1/attributable risk.
Precision
The consistency and reproducibility of a test
(reliability).
The absence of random variation in a test.
Random error-reduces precision in a test.
Inc precision–> dec standard deviation.
Accuracy
The trueness of test measurements (validity). The
absence of systematic error or bias in a test.
Systematic error-reduces accuracy in a test.
Sampling bias
Subjects are not representative of the general
population; therefore, results are not
generalizable. A type of selection bias.
Late look bias
Information gathered at an inappropriate
time-e.g., using a survey to study a fatal
disease (only those patients still alive will be
able to answer survey)
Procedure bias
Subjects in different groups are not treated the
same-e.g., more attention is paid to treatment
group, stimulating greater adherence
Lead time bias
Early detection confused with t survival; seen
with improved screening (natural history of
disease is not changed, but early detection
makes it seem as though survival Inc)
Observer expectancy effect
Occurs when a researcher’s belief in the efficacy
of a treatment changes the outcome of that
treatment
Expecting results your way, lol
Hawthorne effect
Occurs when the group being studied changes
its behavior owing to the knowledge of being
studied
Mean
average of all values
Median
falls right in the middle of all values
mode
the number that occurs most frequently
