URS 6806: Primary data collection

[Chapters covered in this section: 5-8]

Sampling Methods

• Non-probability sampling: Intentional selection
  • Purposive sampling
  • Snowball sampling
  • Quota sampling
• Probability sampling: all items have an equal chance of being selected
  • Random sampling
  • Systematic sampling
  • Stratified sampling
• Multistage Cluster sampling

Determining Sample Size

n=p*(1-p)*(z/a)^2 where

n=sample size;
p=proportion of population in 1 category of a dichotomous variable;
z=standard score for a given confidence level;
a=accuracy

Surveying

• Mailed questionnaires
• Telephone surveys: Random Digit Dialing
• Internet Surveys
• In-person interviews: structured interviews; indepth (intensive) interviews
• Focus groups
• Simple observation

Designing Questions

• Survey questions and research models: Questions should be directly linked to the research variables in Research Model
• Types of questions: Factual, behavioral, opinion, knowledge
• Questionnaire structure:
  • Open and closed ended questions
  • Contingency and filter questions
• Question wording and formatting
  • Biased/ Leading questions
  • Question sequence
  • Questionnaire efficiency

Human Subjects consideration

• Ethical treatment: Informed consent of subjects; privacy and confidentiality
• Preservation of data
• Institutional Review Board Reviews: Expedited vs Non-expedited