SW 5050: Session 1

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SW 5050 Session 1

• Review and Sampling

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Overview

• Syllabus- Decision about assignments
• Review SW 5020
• Posttest of Survey
• Introduction to Sampling
• Types of sampling
• Probability sampling
• Non probability sampling

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REVIEW 5020
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RESEARCH DEFINED

• Research is the use of standardized
  procedures, guided by a scientific mode of
  inquiry, in the search for knowledge in order to
  enhance understanding, prediction, and control.

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STANDARDIZED PROCEDURES??
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THE RESEARCH PROCESS

• Problem Formulation
• Methodology
• Data Collection
• Data Analysis
• Interpretation

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Methodology

• Design
• Sampling Plan
• Instrumentation (Measurement)
• Plan for Data Analysis

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SW 5050 Session 1

• SAMPLING

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Sampling Definitions

• Population
• All possible cases. The whole or totality with
  which research is concerned
• Sample
• One or more elements selected from a population
  for the purpose of study.
• Sampling
• Process of selecting participants. One
  takes/draws a portion of a population because of
  reality constraints.

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Categories of Sampling

• Probability Sampling
• Also known as random sampling
• Highly precise, scientific technique
• Able to calculate sampling error
• Chance dictates selection
• Speaks directly to the issue of external validity
• Must have a sampling frame

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Categories of Sampling

• Non-probability Sampling
• Also known as non-random sampling
• Much less scientific and precise
• Self-selection or selection by researcher
• Serious problems with external validity
• Cannot calculate sampling error
• No sampling frame

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Non-Probability Sampling Strategies

• Convenience Sampling
• Purposive Sampling
• Snowball Sampling
• Quota Sampling

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Probability Sampling Strategies

• Simple Random Sampling
• Systematic Random Sampling
• Stratified Random Sampling

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Probability Sampling Strategies (continued

• Simple Random Sampling
• Each element in the population has an equal
  chance of being selected
• Sampling frame required
• Random numbers table employed

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Probability Sampling Strategies (continued

• Systematic Random Sampling
• Variation of simple random sampling
• Every nth element from the sampling frame is
  selected and included in the sample
• Must create a sampling interval

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Probability Sampling Strategies (continued)

• Stratified Random Sampling
• Population is divided into strata, based on
  important characteristics
• Simple random sample is drawn from each stratum
• Proportionate vs. disproportionate