Stats Flashcards
% Annual preterm births in US
10%
(7.3% late (34+), 2.8% early)
% women raped in lifetime in US
1 in 5 (19%)
type I error
find there is a difference when there really isn’t
false positive
- reject the null incorrectly
- typically use .05 (or .01)
type II error
find no difference when there really is
false negative
power associated with what kind of error
type II error
- sample size
what affects power of a study
sample size
significance level desired
standard deviation
effect size
symbol for type 1 error
alpha
symbol for type 2 error
beta
symbol for power
1 - beta
% under the curve for normal bell for 1 standard deviation
68%
% under the curve for normal bell for
2 standard deviation
95%
% under the curve for normal bell for 3 standard deviation
99%
in normal distribution curve, mean, median, and mode are
all the same
what does confidence interval mean
there is that % of the samples that fall somewhere within the range
what is the null hypothesis
there is no difference
- you want to disprove this
what is the alternative hypothesis
what you want to prove
what is sensitivity
likelihood that if you have the disease, the test is positive
(if you have disease, we’ll pick it up)
what is specificity
likelihood that if you don’t have the disease, you’ll test negative
(if you don’t have disease, it won’t pick it up)
NPV
of those who test negative, how many don’t have the disease
PPV
of those who test positive, how many have the disease
false positive RATE
1 - specificity
false negative RATE
1 - sensitivity
what values depend on disease prevalence
npv & ppv
T-test used to compare
means of two samples of normally distributed data
