BIOSTATS Flashcards
Sensitivity
TP/ (TP+FN)
probability of a disease person testing positive
Specificity
TN/(TN+FP)
probability of a non diseased person testing negative
Positive likelihood ratio
Sensitivity/ (1-Specificity)
ratio representing the likelihood of having the disease given a positive result
Negative likelihood ratio
(1-Sensitivity)/Specificity
ratio representing the likelihood of having the disease given a negative result
Post-test odds
Pre-test odd * LR
ANOVA
the mean values of a continuous variable in several groups (categorical variable) are being compared
Fischer’s exact test
used to study the association between 2 categorical variables when the number of observations is small (ie: treatment result [success/failure] and gender [man/woman])
McNemar test
compares the difference between 2 paired proportions, patients serve as their own control (ie: mean blood pressure before and after treatment in the same subjects)
Paired t test
test the difference between 2 paired means; patients serve as their own control (ie: mean blood pressure before and after treatment in the same subjects)
Pearson chi squared test
used to compare the association between categorical variables; however, this study is assessing a continuous variable (ie: left ventricular wall thickness)
Likelihood ratio
the probability of a given test result occurring in a patient with a disorder compared to the probability of the same result occurring in a patient without the disorder
positive predictive value
PPV = TP/ (TP + FP)
the probability that the disease the present given a positive result
negative predictive value
NPV = TN/ (TN + FN)
the probability that the disease is absent given a negative result
relative risk
risk of exposed/risk of unexposed
attributable risk percent
(RR-1)/RR
