1. 1 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman M ARIO F. T RIOLA E IGHTH E DITION E LEMENTARY S TATISTICS Section 1-4 Design of Experiments

2. 2 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman  Observational Study observing and measuring specific characteristics without attempting to modify the subjects being studied Definitions

3. 3 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman  Experiment apply some treatment and then observe its effects on the subjects Definitions

4. 4 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman Designing an Experiment  Identify your objective  Collect sample data  Use a random procedure that avoids bias  Analyze the data and form conclusions

5. 5 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman  Confounding occurs in an experiment when the effects from two or more variables cannot be distinguished from each other Definitions

6. 6 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman  Replication used when an experiment is repeated on a sample of subjects that is large enough so that we can see the true nature of any effects (instead of being misled by erratic behavior of samples that are too small) Definitions

7. 7 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman  Random Sample members of the population are selected in such a way that each has an equal chance of being selected Definitions

8. 8 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman  Random Sample members of the population are selected in such a way that each has an equal chance of being selected  Simple Random Sample (of size n ) subjects selected in such a way that every possible sample of size n has the same chance of being chosen Definitions

9. 9 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman Random Sampling - selection so that each has an equal chance of being selected

10. 10 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman Systematic Sampling - Select some starting point and then select every K th element in the population

11. 11 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman Hey! Do you believe in the death penalty? Convenience Sampling - use results that are readily available

12. 12 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman Stratified Sampling - subdivide the population into subgroups that share the same characteristic, then draw a sample from each stratum

13. 13 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman Cluster Sampling - divide the population into sections (or clusters); randomly select some of those clusters; choose all members from selected clusters

14. 14 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman  Random  Systematic  Convenience  Stratified  Cluster Methods of Sampling

15. 15 Chapter 1. Section 1-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman  Sampling Error the difference between a sample result and the true population result; such an error results from chance sample fluctuations.  Nonsampling Error sample data that are incorrectly collected, recorded, or analyzed (such as by selecting a biased sample, using a defective instrument, or copying the data incorrectly). Definitions