1. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 1 Methods of Producing Data Sampling: drawing subsets from the population Experimentation: impose a change and measure the result Simulation: numerical facsimile of real-world phenomena Census: using measurements from entire population Survey:asking questions

2. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 2 Simple Random Sample of n measurements: every sample of size n has equal chance of being selected every item in the population has equal chance of being included

3. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 3 Not random sampling: asking for volunteers to respond to a survey choosing the first five customers in a store

4. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 4 Random sampling: drawing names “from a hat” using a random number table to select sample using a random number generator

5. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 5 Simulation Provides arithmetic imitation of “real” phenomenon Random number table may be used

6. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 6 Sampling with replacement The same number may be selected for a sample more than one time.

7. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 7 Other sampling techniques Stratified Sampling Systematic Sampling Cluster Sampling Convenience Sampling

8. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 8 Stratified Sampling Population is divided into groups (“strata”) Random samples are drawn from each group

9. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 9 Systematic Sampling Population is arranged in sequential order. Select a random starting point. Select every “kth” item.

10. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 10 Cluster Sampling Population is divided into sections Some sections are randomly selected Every item in selected sections is included in sample

11. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 11 Convenience Sampling Use whatever data is readily available. Risk severe bias.

12. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 12 Which sampling technique is described? College students are waiting in line for registration. Every eighth person in line is surveyed. Systematic sampling

13. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 13 Which sampling technique is described? College students are waiting in line for registration. Students are asked to volunteer to respond to a survey. Convenience sampling

14. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 14 Which sampling technique is described? In a large high school, students from every homeroom are randomly selected to participate in a survey Stratified sampling

15. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 15 Which sampling technique is described? An accountant uses a random number generator to select ten accounts for audit. Simple random sampling

16. Copyright (C) 2002 Houghton Mifflin Company. All rights reserved. 16 Which sampling technique is described? To determine students’ opinions of a new registration method, a college randomly selects five majors. All students in the selected majors are surveyed. Cluster sampling