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# Statistical Sampling

Statistical Sampling. Part II – Language and Technique. This video is designed to accompany pages 41-76 in Making Sense of Uncertainty Activities for Teaching Statistical Reasoning Van- Griner Publishing Company. 6. 8. 1. 10. 12. 2. 4. 7. 5. 11. 3. 5. 9. 2. 10. 8.

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## Statistical Sampling

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1. Statistical Sampling Part II – Language and Technique

2. This video is designed to accompany pages 41-76 in Making Sense of Uncertainty Activities for Teaching Statistical Reasoning Van-Griner Publishing Company

3. 6 8 1 10 12 2 4 7 5 11 3 5 9 2 10 8 Basic Language List of Individuals 1 2 3 4 5 6 7 8 9 10 11 12 Sample - Subject/items that you are able to measure/interview. Chosen from population. Population - Larger collection of subjects/items that you are interested in understanding something about.

4. 4 2 1 10 12 8 6 7 5 11 3 5 9 2 10 8 Critical Distinction Remember S-S Statistic – number that describes the sample. E.g. observed proportion in sample who answered “Yes” Sample Remember P-P Population Parameter – number that describes the population. E.g. true proportion of all U.K. students who would answer “Yes” to “Do you support gay marriage?”

5. Identification of Terms Parameter - true, unknown percentage of ALL Americans who would have said they supported stricter gun laws, if all had been asked. Americans and Their Guns Title: Poll: Majority of Americans Back Stricter Gun Laws Authors: Sarah Dutton, Jennifer De Pinto, Anthony Salvanto, Fred Backus, Leigh Ann Caldwell Source:CBS News January 17, 2013 As the president outlined sweeping new proposals aimed to reduce gun violence, a new CBS News/New York Times poll found that Americans back the central components of the president's proposals, including background checks, a national gun sale database, limits on high capacity magazines and a ban on semi-automatic weapons. Asked if they generally back stricter gun laws, more than half of respondents - 54 percent - support stricter gun laws …. That is a jump from April - before the Newtown and Aurora shootings - when only 39 percent backed stricter gun laws but about the same as ten years ago. … This poll was conducted by telephone from January 11-15, 2013 among 1,110 adults nationwide. Phone numbers were dialed from samples of both standard land-line and cell phones. The error due to sampling for results based on the entire sample could be plus or minus three percentage points. Population (All Americans) Statistic Sample

6. Simple Random Sampling A simple random sample (SRS) of size n consists of n individuals chosen from the population in such a way that every set of n individuals had the same chance of being chosen.

7. 7 8 1 10 12 2 4 6 5 8 11 3 5 9 2 10 Practical Selection Tool SRS of size n from N subjects? Label objects 1 to N Use http://www.randomizer.org

8. 7 8 1 10 12 2 4 6 5 8 11 3 5 9 2 10 Subtle and Critical Keys to confidence in your parameter estimate? The probabilistic nature of the sample selection Some really neat mathematics

9. Common Confusion A “fair” sample in a probabilistic sense is NOT a cross-sectional sample. One of least understood, but most critical interpretations of what it means to sample “fairly.”

10. One-Sentence Reflection A probabilistic sample like an SRS is a critical step in estimating a population parameter with a sample statistic.

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