Biostats and Pharmacoeconomics Flashcards
Continuous data categories
Ratio and interval data
Examples of ratio data
age, weight, height, time, blood pressure
Examples of interval data
temperature scales
Discrete data categories
nominal and ordinal
Examples of nominal data
gender, ethnicity, marital status, mortality
Examples of ordinal data
NYHA Functional Class I-IV, 0-10 pain scale
Comparing difference data (means): when is it statistically significant?
When the CI doesn’t cross 0
Comparing ratio data (RR, OR, HR): when is it statistically significant?
When the CI doesn’t cross 1
Type I errors are what?
False positives
Type 2 errors are what?
False negatives
Study power definition
Probability that a test will reject the null hypothesis
RR=1 interpretation
No difference in risk of the outcome between the groups
RR >1 interpretation
greater risk of the outcome in the treatment group
RR <1 interpretation
lower risk of the outcome in the treatment group
Wording for RR
“AS likely vs. control”
RRR definition
Indicates how much risk is REDUCED in treatment group
RRR interpretation wording
“LESS likely vs. control”
ARR definition
The reduction in risk and the incidence rate of the outcome
ARR interpretation wording
“X out of every 100 patients will benefit”
NNT definition
How many patients need to be treated before 1 patient benefits
NNT rounding rules
Round UP, you don’t want to underestimate how many people need to be treated!
NNT interpretation
“For every X patient who receives Y treatment, Z (adverse outcome) is prevented in one patient”
NNH definition
How many patients need to be treated before 1 patient gets harmed
NNH rounding rules
ROUND DOWN, you don’t want to underestimate the potential harm of an intervention!
NNH interpretation
“One case of Z (adverse outcome) is expected to occur for every X patients who take Y (treatment)”