1. 1. value of information - gains / losses - nearness to breakeven 3. degree of accuracy 4. resources/Time 5. advance knowledge of population 6. national vs. local 7. need for statistical analysis Sample Size Determination

2. Sample Size previous practice magic number minimum cell sizes resource limits expert judgement

3. Improving Sample Efficiency Measures of cost-benefit 1.stratification samples variance reduction 2. clustering samples cost reduction

4. Stratified Sampling

5. Reasons for Stratification strata are of interest variances differ costs differ

6. Cluster Sampling

7. Examples of Kinds of Clusters Population Elements U.S. adult elements College seniors Elementary school students Manufacturing firms Airline travelers Hospital patients Possible Clusters counties localities census tracts blocks households colleges schools counties localities plants airports planes hospitals

8. Mall Samples choosing the mall sampling at the mall –where? –when? adjusting for frequency of visit

9. Computing Sampling Errors Use of replication Availability of computer programs