Block Sampling, also known as “block judgment sampling,” is a non-probabilistic sampling technique often used in auditing and quality control. In this method, blocks of consecutive items are selected once an initial item is chosen. The subsequent items within the block are included automatically, without the randomness typically associated with probabilistic sampling methods.
Types of Block Sampling
- Fixed Block Sampling: A predetermined fixed number of items in each block, chosen sequentially.
- Variable Block Sampling: The size of the blocks may vary, though each block is still selected consecutively after the initial item.
Special Considerations
- Bias Concern: Block sampling can introduce bias, as selecting consecutive items may not represent the entire population adequately.
- Application Specificity: More suited for homogenous populations where selected blocks can reliably represent the entire set.
Historical Context
Block sampling has its roots in traditional auditing practices, where manual selection was prevalent. Over time, it has become common in both financial and operational audits due to its simplicity and ease of implementation.
Applicability
In Auditing
Auditors often use block sampling to select specific transaction periods, making it easier to scrutinize continuous operational phases without random sampling complications.
In Quality Control
Used to select samples within batches produced consecutively, allowing for focused inspection on particular production runs.
Comparison with Related Terms
- Cluster Sampling: Divides the population into separate groups (clusters) and randomly selects entire clusters for study. Unlike block sampling, clusters do not require sequential order.
- Systematic Sampling: Selects every k-th item from a random starting point in the population. Block sampling, however, chooses consecutive items after an initial one.
FAQ
Q. Is block sampling the same as cluster sampling?
A. No, while both methods involve groups of items, cluster sampling uses randomly selected clusters, while block sampling uses consecutively selected blocks.
Q. What are the major advantages of block sampling?
A. Block sampling simplifies the selection process and reduces time and effort compared to more randomized methods.
Summary
Block Sampling is a judgmental sampling technique where, after choosing an initial item, subsequent items in a block are automatically included. Despite its simplicity, it is essential to consider its potential biases and applicability, especially when representing diverse populations.
References
- Financial Auditing Guidelines. Auditing Standards and Procedures.
- Bouvier, A., Principles of Sampling Techniques in Auditing and Quality Control.
Block Sampling remains a crucial yet straightforward tool in auditing and quality control, balancing between simplicity and accuracy.
