16 terms

point estimator

a statistic that provides an estimate of a population parameter

point estimate

the value of a statistic from a sample

C% confidence interval

gives an interval of plausible values for a parameter

point estimate +/- margin of error

point estimate +/- margin of error

margin of error

shows how close we believe our guess is, based on the variability of the estimate in repeated SRSs of the same size

critical value x standard deviation of statistic

critical value x standard deviation of statistic

confidence level C

In C% of all possible samples, the method would yield an interval that captures the true parameter value.

interpretation of confidence interval

We are C% confidence that the interval from ___ to ___ captures the true population [parameter in context].

conditions for estimating population parameters

SRS, Independent, Normal

standard error

when the standard deviation of the statistic is estimated from data

The four step process

State, Plan, Do, Conclude

degrees of freedom

for a t-distribution, this is required in order to find the critical value

n-1

n-1

z*

critical value for proportions

t*

critical value for means, population standard deviation unknown

Normal condition for means

CLT, n>= 30

if n<30, then no skewness or outliers if graphed

if n<30, then no skewness or outliers if graphed

Normal condition for proportions

np>10, n(1-p)>10

Independent condition

sample size is less than 10% of the population

random condition (SRS)

the sample must come from a well-designed random sample or randomized experiment