1. Do Now Return to your groups from Friday and work to finish your projects. If you were not here Friday, tell Mr. Madonna and he will get you into a group. Lastly, one group walked away with a pack of cards. It needs to come back.

2. Yesterday Systematic Sampling – selecting a starting point and then select every kth (such as every 50 th ) element of a population. Convenience Sampling – we use the results that are easiest to get. Stratified Sampling – we subdivide the population into at least two groups so that subjects in the same group share the same characteristics, and we take an equal number from each. Cluster Sampling – we first divide the population area into sections then randomly select some of those clusters, taking all the members from the selected clusters.

3. Objectives 14.February.2011 Students will be able to… Evaluate different sampling styles.

4. Agenda Finish Project (15 min) Review (10 min) What sampling is best (15 min)

5. Hwork This was due last Friday: Pg. 32, #17-30

6. Hwork 17. Cluster 18. Stratified 19. Convenience 20. Systematic 21. Random 22. Stratified 23. Cluster 24. Random 25. Random. A group of n returns, half from Monday, half from Tuesday can never exist. 26. Not random. While there is room for variation, arrival times aren’t random. 27. Not random. 28. Random. A group of 40 people could never be 40 men. 29. Simple random. 30. Simple random.

7. Sampling Why do we sample? Because it usually isn’t practical to survey an entire population. Is convenience sampling ever okay? It works for preliminary study, but usually not for anything final or formal. What sampling is best? We can always try to combine different sampling strategies.

8. Error Sampling Error – the difference between a sample result and the whole population. This is the result of chance, not a flaw in the sampling. Non-Sampling Error – occurs when the data is collected incorrectly because your measurements were defective (not precise) or a biased sample. Hwork Tonight: #33 on pg. 33. This is only one problem, so that should indicate it’s a big one.