Statistics Flashcards
What is nonparametric data?
Data that does not fit the normal distribution. It is often discrete (nominal or ordinal)
How should nonparametric data be analyzed?
Chi square or Mann-Whitney U
What is type I error?
Incorrectly rejects the null, ie interpreted as a difference when there is none
What is type II error?
Incorrectly accepts the null, ie interpreted as equal when in fact a difference exists
What causes type II error?
sample size too small
What is variance?
The spread of data around the mean
When should a t test be used?
When data is quantitatve and you are comparing means.
When should Students t test vs a paired t test be used?
student’s t test: independent groups
paired t test: dependent groups–ie, before and after intervention
When should ANOVA be used?
When comparing means from more than 2 groups.
Formula for relative risk?
incidence in exposed/incidence in unexposed
Formula for power?
Power = probability of making the correct conclusion = 1 - probability of making type II error
Prevalence is
of people with disease in a population
Incidence is
of new cases over period of time
Formula for sensitivity?
true positives/(true pos + false negatives)
Formula for specificity?
true negatives/(true neg + false positives)
