DS212_Chap7_Sampling_and_Sampling_Dist

# DS212_Chap7_Sampling_and_Sampling_Dist - C hapte 7 S pling...

This preview shows pages 1–10. Sign up to view the full content.

1 Chapter 7: Sampling and Sampling Distributions Sada Soorapanth Spring 2010

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 Statistical Inference x Population Parameters μ , σ 2 , p μ = population mean σ 2 = population variance p = population proportion = sampleaverage s 2 = samplevariance = sampleproportion x Sample Statistics p s x , , 2 Collect samples Estimate population parameters Sample Statistics p s x , , 2 Sample Statistics p s x , , 2 p
3 Reasons for Sampling Sampling can save time and money. For given resources, sampling can broaden the scope of the data set. Because the research process is sometimes destructive, the sample can save product. If accessing the population is impossible; sampling is the only option.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
4 Samples ProvideEstimates of Population A tiremanufacturer developed a new tire designed to providean increasein mileageover thefirm’s current lineof tires. To estimatethemean number of miles provided by the new tires, the manufacturer selected a sampleof 120 new tires for testing. The test results provided a samplemean of 36,500 miles. Hence, an estimateof themean tiremileage for the population of new tires was 36,500 miles
5 Random Versus Nonrandom Sampling Random sampling Every unit of thepopulation has thesameprobability of being included in the sample. A chancemechanism is used in theselection process. Eliminates bias in theselection process Also known as probability sampling Nonrandom Sampling Every unit of thepopulation does not havethesameprobability of being included in thesample. Open to selection bias Not appropriatedata collection methods for most statistical methods Also known as nonprobability sampling

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
6 Random Sampling Techniques Simple Random Sampling Stratified Random Sampling Systematic Random Sampling Cluster (or Area) Sampling
7 SimpleRandom Sampling from a Finite Population A simplerandomsampleof sizen froma finitepopulation of sizeN is a sample selected such that each possible samplehas thesameprobability of being selected Steps 1. Number each unit in thepopulation from 1 to N. 2. Usea random number tableor a random number generator to select n distinct numbers between 1 and N, inclusively.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
8 SimpleRandomSample(FinitePopulation): Step 1: Numbered Population 01 Alaska Airlines 02 Alcoa 03 Ashland 04 Bank of America 05 BellSouth 06 Chevron 07 Citigroup 08 Clorox 09 Delta Air Lines 10 Disney 11 DuPont 12 Exxon Mobil 13 General Dynamics 14 General Electric 15 General Mills 16 Halliburton 17 IBM 18 Kellog 19 KMart 20 Lowe’s 21 Lucent 22 Mattel 23 Mead 24 Microsoft 25 Occidental Petroleum 26 JCPenney 27 Procter & Gamble 28 Ryder 29 Sears 30 Time Warner N = 30 n = 6
9 SimpleRandomSample(FinitePopulation): Step 2: RandomNumber Table 9 9 4 3 7 8 7 9 6 1 4 5 7 3 7 3 7 5 5 2 9 7 9 6 9 3 9 0 9 4 3 4 4 7 5 3 1 6 1 8 5 0 6 5 6 0 0 1 2 7 6 8 3 6 7 6 6 8 8 2 0 8 1 5 6 8 0 0 1 6 7 8 2 2 4 5 8 3 2 6 8 0 8 8 0 6 3 1 7 1 4 2 8 7 7 6 6 8 3 5 6 0 5 1 5 7 0 2 9 6 5 0 0 2 6 4 5 5 8 7 8 6 4 2 0 4 0 8 5 3 5 3 7 9 8 8 9 4 5 4 6 8 1 3 0 9 1 2 5 3 8 8 1 0 4 7 4 3 1 9 6 0 0 9 7

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern