Flashcards in Statistics Deck (13):
Variance = SD squared
Standard Error =
SD / Square root (n)
Positive skew - highest to lowest mean median mode
Positive skew, Mean > Median > Mode
Mode > Median > Mean.
The skew pulls the mean and median in its direction.
The mode is the least changed by skew.
Mean = Median = Mode
Type 1 error
rejecting a correct null hypothesis,
false positive error
Type 2 error
not rejecting an incorrect null hypothesis.
AR = a/(a+b) - c/(c+d)
AR = Prevalence of disease in the exposed group - prevalence of the disease in the non-exposed
Absolute risk reducion
The reverse of the attributable risk.
ARR = c/(c+d) - a/(a+b)
Percentage of people who got the disease with no intervention - the percentage of people who got the disease after the treatment.
Number needed to treat
NNT = 1/ARR
Pirates love treats ARR!
Number needed to harm
NNR = 1/AR
LR+, positive likelihood ratio
LR+ = sensitivity/1-specificity = true positive % / false positive %