Intro to Evidence Based Medicine Flashcards
EBM triad domains
- clinical judgement
- best relevant evidence
- pt’s preferences & values
types of empirical evidence
observations = data grounded in physical reality quantitative = chemical & biological processes that involve the use of stats
function of stats
- Summarize a set of data
- Measure the degree of association between 2 variables
- Control potential confounding variables
- Predict future health outcomes
- Distinguish in sample data between genuine trends and random variability
descriptive statistics
frequency & percentage for categorical variables
ex) pie charts or bar graphs of BMI category
continuous variables
mean
standard deviations
measure of effect size
quantifies effect of X on Y
effect can be:
-causal
-statistical relationship
purpose of clinical research
investigates the causes of disease, factors that prevent disease, and treatments that restore health
-empirical investication
categorical variables
BMI
box plot
graphical technique which is useful for determining if the data are skewed and for detecting outliers
whiskers in a box plot
drawn from each end of the box to a point
-indicates outliers by the IQR
interquartile range
distance between the 75th and 25th percentiles in a box plot
top whisker in box plot
1.5 IQR above the 75th percentile
bottom whisker in box plot
below the 25th percentile
mild outliers
more than 1.5 IQR
-represented as circles in a box plot
extreme outliers
more than 3.0 IQR
-represented as asterisks in a box plot
effect
refers to either a causal or a statistical relationship
Risk Reduction Measures
- The more a treatment reduces risk,
- The greater will be the ARR
- The greater will be the RRR
- The smaller will be the NNT
confounding variables
methods of statistical control
-referred to as Z
statistical control
quantify the degree of relationship between X and Y after taking into account a third variable (Z) that is related to both
regression analysis
popular method for statistically controlling confounding variables
prognostic statistics
Predict future health-related outcomes
-based on various characteristics of that patient
inferential statistics
Distinguish in sample data between genuine trends and random variability
-help researchers to decide whether what was found to be true of the sample
*
Is likely to be true of the population?
or
Was just due to random sampling variability (chance)?
test statistics
generate 95% confidence intervals and P values
types of inferential statistics (test statistics)
- Z (generated by the Z-test)
- t (generated by the t-test)
- F (generated by the F-test)
- Χ2 (generated by the chi-square test)
- Wald (generated by the Wald test)
* All are used to compute 95% CIs and P values.