Ethics/Statistics Flashcards
can you perform practice procedures on a newly deceased patient
Yes, but you must gain permission from patient before dying or a patient’s family member
what is information bias
bias introduced by imprecise measurement methods of exposure or outcome
difference between two sample t-test and two sample z-test
t-test compares means between two samples
z-test compares means between two populations (not frequently used)
what is ANOVA
Analysis of Variance: used to compare three or more means
what is the chi square test used for
to compare categorical data or proportions
what are the equations for relative rate and odds ratio
RR= [(a/a+b)/(c/c+d)]
OR=ad/bc
how do you calculate attributable risk percentage
ARP= (relative risk - 1) / (relative risk)
what is selective survival bias
seen in case control studies; selecting patients from the entire population as opposed newly diagnosed patients will give you a higher proportion of patients with less severe disease since most of the severe cases would have died already
what happens to the PPV and NPV of a test if a population has a high prevalence of the tested disease?
what about if a population has low prevalence of the tested disease?
high prevalence population: PPV increases, NPV decreasese (since with a neg test you would still suspect diseas)
low prevalence population: PPV decreases, NPV increases
what’s a quick and easy way to distinguish effect modification from confounding?
stratify by the proposed confounder; if there is no association in either of the stratified groups then the variable you stratified by was a confounder
if you stratify by the variable and there is a strong association found btwn exposure and outcome in one group but not the other than there was likely an effect modification
explain a factorial design
2 or more interventions are studied, with 2 or more independent variables studied within each intervention
explain cluster analysis
involves grouping different data into similar categories or randomization at the level of groups rather than individuals
what is Berkson bias
a form of selection bias in which studies conducted using hospital patients as sample are unrepresentative of entire population
what is attrition bias
a form of selection bias in which a significant amount of subjects are lost to follow up and may differ from those who remain
what kind of bias should you think of when you see a new screening test for a poor-prognosis disease (e.g. cancer)
lead-time bias
