This presentation explores the relationship between populations and representative samples where the samples are considered to be simple random samples

1
Introduction

• This presentation explores the relationship
  between populations and representative samples
  where the samples are considered to be simple
  random samples

2
Population Characteristics

• A Population is shown to the right
• What are its characteristics?

3
Sample Characteristics
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1

• Same Population above right
• Click to take a Sample from the Population
• Is the Sample Representative of the Population?

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9
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8
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14
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19
7
11
21
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4
Sample Characteristics
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• Again, same Population above right
• Click to take another Sample from the Population
• Is this Sample Representative of the Population?

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9
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8
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20
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14
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5
Another Population

• A New Population is shown to the right
• What are its characteristics?

6
Sampling from this Population

• Click to take a sample from the population
• What are the sample characteristics?
• Is the Sample Representative of the Population?

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6
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13
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20
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Conclusions

• Populations usually have many describing
  characteristics
• To be representative, a sample must include all
  characteristics in the same proportions as the
  population
• Random samples will generally have to be larger
  if you want them to represent all population
  characteristics