biostat Flashcards
(46 cards)
formula for RR
relative risk
EER/CER
formula for RRR
1 - RR
ARR formula
CER - EER
OR
EER - CER
[since this is the absolute value]
NNT formula for the duration of the study
1/ARR
NNT for 1 year
NNT x (# of years the study was conducted)
odds ratio (OR) formula
[EER/ENR] / [CER/CNR]
discrete data
generally refers to discrete, countable numbers with no decimals (cannot be divided)
ex: people
continuous data
in contract, is more of a continuum in which use of decimals allows for an infinite number of possible values
e: electrolyte levels
discrete data subtypes
nominal (categorical) data
ordinal (ranked) data
nominal (categorical) data
refers to assigning data to different CATEGORIES based on the occurrence of an outcome
ordinal (ranked) data
refers to data that come in a certain order or ranking but the intervals between the values are not necessarily equal
ex: NYHA classification
continuous data subtypes
interval data
ratio data
*can be expressed using decimals
interval data
refers to measurable data with equal intervals between values. there is no absolute zero
ex: temperature (a “0” temperature has meaning)
ratio data
type of data interval that has an absolute zero
ex: height, weight, hemoglobin level
continuous data tests
t - test
student’s t test
paired t test
analysis of variance (ANOVA) test
t-test
continuous data
means of two groups
ex: cholesterol levels OR HgbA1c
student’s t-test
continuous data
two groups are independent and separate
paired t-test
continuous data
test group acts as its own control (“PAIRED”)
ANOVA test
continuous data
groups of >/= 3 groups are being compared (similar to t-test but there are >/= 3 groups)
CAN BE USED FOR BOTH INDEPENDENT AND PAIRED GROUPS
nominal (categorical) data tests
DISCRETE DATA
chi-square test
McNemar’s test
Cochran’s Q test
chi square test
nominal // discrete
two or more independent groups
ex: the risk of GI bleed is compared in ASA group vs placebo group
McNemar’s test
nominal // discrete
two paired groups
Cochran’s Q test
nominal // discrete
> /= 3 paired groups
ordinal (ranked) data tests
DISCRETE DATA
wilcoxon rank sum test
wilcoxon signed rank test
kruskal-wallis test
friedman test