Epidemiology and statistics Flashcards
Sensitivity
The ability of a test to correctly identify those with a condition.
SENSITIVITY = TP /TP + FN
Specificity
The ability of a test to correctly identify those that do not have a condition.
SPECIFICITY = TN/TN + FP
Standard error of mean ( SEM)
SEM = SD/ square root (n)
Confounding
A variable that correlates with other variables within a study, leading to spurious results.
Correlation
Correlation is used to test for association between variables.
Linear regression
Linear regression may be used to predict how much one variable changes when a second variable is changed.
Type 1 error
the null hypothesis is rejected when it is true
Type 2 error
the null hypothesis is accepted when it is false
P value
p value is the probability of obtaining a result by chance at least as extreme as the one that was actually observed, assuming that the null hypothesis is true. It is therefore equal to the chance of making a type I error
The power of a study
The power of a study is the probability of (correctly) rejecting the null hypothesis when it is false, i.e. the probability of detecting a statistically significant difference
Power = 1 - the probability of a type II error.
Power can be increased by increasing the sample size
The paired t test
The paired t test is appropriate for testing differences of means in a single group.
Log-rank test
Log-rank test can be used to test the difference in relapse rate between the two groups
