Sampling Design and Fieldwork Management
A sample is a subset of a population selected for research. Sampling allows researchers to obtain useful estimates without studying every member of the population. The quality of conclusions depends on how well the sample represents the decision population.
Learning Objectives
- Define population, sampling frame, element, and sample.
- Compare probability and non-probability methods.
- Identify factors affecting sample size.
- Manage fieldwork quality and nonresponse.
Probability Sampling
| Method | Description |
|---|
| Simple Random | Every element has a known and equal selection chance. |
| Systematic | Elements are selected at a fixed interval after a random start. |
| Stratified | The population is divided into groups before random selection. |
| Cluster | Natural groups are selected, then members are studied. |
| Multistage | Selection occurs through several sampling stages. |
Non-Probability Sampling
- Convenience sampling
- Judgment or purposive sampling
- Quota sampling
- Snowball sampling
- Volunteer or self-selection sampling
Fieldwork Quality Controls
- Train interviewers and recruiters consistently.
- Use clear scripts and eligibility rules.
- Monitor interview duration and response patterns.
- Validate a sample of completed interviews.
- Prevent duplicate and fraudulent responses.