STAT 1000 - UNIT 6 EXAM 2025
QUESTIONS AND ANSWERS
Statistical inference - ANS - provides methods for drawing conclusions about a population
from sample data
how "good" of an estimator is Xbar? - ANS - the probability that Xbar = μ is equal to 0,
because of continuity (Xbar is a continuous variable)
- reporting the sample mean alone gives no information as to how accurate we believe our
estimate to be
- instead, we would like to use the sample mean to construct an interval of values to estimate
the population mean μ
95% confidence interval for μ - ANS (xbar - 1.96*σ/√n, xbar + 1.96*σ/√n)
we interpret the 95% confidence interval for μ as follows: - ANS - if we repeatedly took
simple random samples of the same size from the same population and constructed the interval
in a similar manner, 95% of all such intervals would contain the true mean μ of the population
estimate - ANS - best guess at the true value of the parameter we're trying to estimate
margin of error - ANS - reflects how accurate we believe our estimate to be
confidence level, C - ANS - gives the probability that the interval will contain the true value of
the population mean μ
general level C confidence interval formula - ANS xbar ± z*σ/√n
Copyright ©2025 BRIGHTSTARS ALL RIGHTS RESERVED 1
QUESTIONS AND ANSWERS
Statistical inference - ANS - provides methods for drawing conclusions about a population
from sample data
how "good" of an estimator is Xbar? - ANS - the probability that Xbar = μ is equal to 0,
because of continuity (Xbar is a continuous variable)
- reporting the sample mean alone gives no information as to how accurate we believe our
estimate to be
- instead, we would like to use the sample mean to construct an interval of values to estimate
the population mean μ
95% confidence interval for μ - ANS (xbar - 1.96*σ/√n, xbar + 1.96*σ/√n)
we interpret the 95% confidence interval for μ as follows: - ANS - if we repeatedly took
simple random samples of the same size from the same population and constructed the interval
in a similar manner, 95% of all such intervals would contain the true mean μ of the population
estimate - ANS - best guess at the true value of the parameter we're trying to estimate
margin of error - ANS - reflects how accurate we believe our estimate to be
confidence level, C - ANS - gives the probability that the interval will contain the true value of
the population mean μ
general level C confidence interval formula - ANS xbar ± z*σ/√n
Copyright ©2025 BRIGHTSTARS ALL RIGHTS RESERVED 1
