Non-Statistical Sampling, also known as judgmental sampling, is a sampling method where the selection of samples is based on the judgment of the sampler rather than on random selection. This method is often used in auditing and research when statistical sampling is not feasible.
Historical Context
Non-statistical sampling has been utilized historically in fields such as auditing, market research, and quality control when statistical tools were either unavailable or impractical. Prior to the widespread availability of computational tools that facilitated random sampling, non-statistical methods provided a practical means to derive conclusions from data.
Types/Categories
Judgmental Sampling
Judgmental sampling is the primary category under non-statistical sampling, involving the selection of units based on the researcher’s knowledge and expertise.
Convenience Sampling
This type involves choosing samples that are easy to access or contact, often used in exploratory research where representativeness is not the primary concern.
Quota Sampling
Here, the researcher ensures certain characteristics are represented in the sample to the extent they appear in the population, often without employing random selection within these quotas.
Key Events
- Early Use in Auditing: Before the development of statistical sampling techniques, auditors often relied on non-statistical methods to evaluate the accuracy of financial records.
- Development of Sampling Theory: With the formalization of statistical sampling in the early 20th century, non-statistical methods were compared and sometimes integrated with new techniques.
Detailed Explanation
Non-statistical sampling relies on the expert judgment of the sampler to choose sample items. These items are selected based on their perceived representation of the entire population or their significance to the objectives of the audit or research.
Importance
Non-statistical sampling is crucial when:
- Detailed knowledge of the population is available.
- There is a need for rapid decision-making.
- The cost of statistical sampling is prohibitive.
Applicability
- Auditing: Used when certain transactions or accounts are selected for closer inspection based on perceived risk or materiality.
- Market Research: Utilized when targeting specific segments that the researcher is familiar with.
- Quality Control: Applied when inspecting key items or areas that are known to be problem-prone.
Examples
- An auditor choosing specific high-value transactions for review.
- A researcher surveying a convenient sample of customers at a particular store location.
- Quality control inspectors focusing on specific defect-prone items.
Considerations
- Bias: Since selection is not random, there is an inherent risk of bias.
- Reliability: Results from non-statistical samples can be less reliable and not generalizable.
- Applicability: Best applied when the researcher has significant expertise or when exploratory insights are needed.
Related Terms
- Statistical Sampling: Involves random selection and allows for inferential statistics.
- Random Sampling: Each item in the population has an equal chance of being selected.
- Systematic Sampling: Selection of every nth item in the population.
- Stratified Sampling: Division of population into subgroups and random sampling within these groups.
Comparison
| Feature | Non-Statistical Sampling | Statistical Sampling |
|---|---|---|
| Selection Method | Judgment-based | Random or systematic |
| Risk of Bias | High | Low |
| Generalizability | Limited | High |
| Cost | Often lower | Can be higher |
Interesting Facts
- Non-statistical sampling can sometimes provide quicker results in time-constrained environments.
- It often relies on the expertise of the sampler, which can be an advantage if the sampler has significant insight.
Inspirational Stories
One notable instance of effective non-statistical sampling is the use of judgmental sampling by auditors during the Enron scandal. Experienced auditors identified critical areas of risk without relying solely on statistical methods.
Famous Quotes
“The selection of a few key items often reveals more than a random assortment.” – Anonymous Auditor
Proverbs and Clichés
- “Trust your instincts”: Emphasizes the role of expert judgment in non-statistical sampling.
- “Knowledge is power”: Highlights the importance of using expertise to guide sampling.
Expressions, Jargon, and Slang
- [“Cherry-Picking”](https://financedictionarypro.com/definitions/c/cherry-picking/ ““Cherry-Picking””): Selecting the most advantageous items from a group.
- “Gut Feeling Sampling”: Informal term for relying on intuition in sample selection.
FAQs
Is non-statistical sampling reliable?
When is non-statistical sampling most useful?
References
- Cochran, W.G. (1977). Sampling Techniques. Wiley.
- Arkin, H. (1974). Handbook of Sampling for Auditing and Accounting. McGraw-Hill.
- The Institute of Internal Auditors. Audit Sampling. [Online Resource]
Summary
Non-statistical sampling, or judgmental sampling, is a valuable technique where sample selection is based on the judgment and expertise of the sampler. While it lacks the statistical rigor of random sampling methods, its use in auditing, market research, and quality control demonstrates its practical importance. Consideration of its limitations and the potential for bias is essential for effectively leveraging this sampling method.
