Sample Surveys

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Sample Surveys

• May involve questionnaire type information or
  other measuring instruments
• There is no Treatment applied randomly
• There may be different groups and questions about
  differences can be addressed

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ExamplesHow do we survey the following-

• Government surveys of business etc.
• Veterinary Association surveys of members
• Soil samples of a paddock, a Region, the country
• Samples of Rabbits, Sheep etc.
• Faecal egg samples

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Representative Sample

• Representative of what?
• How do we know?

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Non Response

• The problem
• In questionnaire type surveys
• In other surveys
• Possible solutions

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Estimates from Stratified Surveys

• In a survey we have 3 strata
• Large Medium and Small

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• Estimated total for whole population
• 2021.6 2998.3 2219.2 7239.1
• Total population size
• 28 113 456 597
• Hence mean 7239.1 / 597 12.13
• The standard deviation requires a little more
  calculation.

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Some ideas for Non Response

• Collect more data!
• Post Stratification
• Weight responses - those under represented are
  weighted higher than others

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