point estimator
a statistic that provides an estimate of a population parameter
confidence interval
an interval of plausible values for a parameter based on sample data (most common is 95%)
confidence level C
the overall success rate of method used to calculate confidence interval - “we are C% confident that interval _ captures % of parameter.”
margin of error
how far (at most) estimate is expected to vary from point estimator in C% confidence interval
decreasing margin of error…
confidence level decreases; sample size increases
critical value
a multiplier that makes interval wide enough to have the stated capture rate
3 conditions for validity of confidence interval p…
random sample
large counts: np^ ≥ 100 & n(1-p^) ≥ 100
10%: n < 0.10N
standard error
estimate of the standard deviation of a statistic via data
confidence interval
point estimate ± margin of error OR statistic ± critical standard error
confidence interval for p1-p2
statistic ± (critical value)(standard deviation of statistic)
randomized comparative experiment
subjects are randomly assigned to different treatment groups, response variable is tested.