1. Business Statistics - QBM117 Revising interval estimation

2. Objective w To develop confidence in identifying the correct formula to use when calculating an interval estimate.

3. Identifying the parameter to be estimated w In this subject we need only concern ourselves with estimating the population mean , or the population proportion p. w Generally it is clear from the question, which parameter we are estimating, if we read it carefully enough.

4. Two confidence interval estimators of  w If  is known, the confidence interval estimator of the population mean  is There are two different interval estimators of the population mean, and the basis for determining which method is appropriate is quite simple. w If  is unknown and the population is normally distributed, the confidence interval estimator of the population mean  is When d.f > 200 we approximate t by thevalue.

5. Only one confidence interval estimator of p w There are is only one confidence interval estimator of the population proportion so there is no choice. w One condition however must be satisfied before we know that p hat will have an approximate normal distribution.

9. Chapter 10 Sections 10.1 - 10.2 or Chapter 9 Sections 9.1 – 9.2 abridged Reading for next lecture