Determining the Sample Plan

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Determining the Sample Plan

• Sampling - Use of a small number of items in a
  population to make conclusions about the whole
  population.

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Determining the Sample Plan

• Sample A subset of a larger population.

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Determining the Sample Plan

• Sample Frame Working list of the entire
  population.

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Determining the Sample Plan

• Population Any complete group sharing some
  common set of characteristics.

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Determining the Sample Plan

• Population element One member of the
  population.

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Determining the Sample Plan

• Census An investigation of all individual
  elements in a population.

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Types of samples

• Probability - Population members have a known
  chance of being selected into the sample.

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Probability Samples

• Simple random sampling Each element in the
  population has a known and identical chance of
  being included in the sample.

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Probability Samples

• Systematic sampling Starting point is selected
  by random process and every nth number on the
  list is selected.

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Probability Samples

• Stratified sampling
• 1. Researcher chooses strata (subgroups).
• 2. Subsamples are drawn from within each stratum
  (subgroup) using simple random or systematic
  sampling procedure.

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Probability Samples

• Cluster sampling
• 1. Researcher chooses strata (subgroups).
• 2. Simple random or systematic sample of
  subgroups is drawn.

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Types of samples

• Nonprobability - Probability of selecting any
  specific population element is unknown.

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Nonprobability sampling

• Convenience sampling Researcher obtains
  individuals who are most conveniently available.

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Nonprobability sampling

• Judgment sampling - Researcher selects sample
  based on his or her experienced judgment.

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Nonprobability sampling

• Quota sampling technique designed to ensure
  that various subgroups in a population are
  represented.

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Nonprobability sampling

• Snowball (referral) sampling researcher uses
  referrals to locate rare or hard-to-find
  populations.

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Sample Size Determination Methods

• Arbitrary Approach

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Sample Size Determination Methods

• Conventional Approach

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Sample Size Determination Methods

• Cost Basis Approach

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Sample Size Determination Methods

• Confidence Interval Approach