Simple Random Sampling
Definition
A design in which every possible subset of a given size has an equal probability of being selected. It requires a complete sampling frame listing all units in the population and is the reference design for most statistical inference formulas.
- Selection rule
- Every possible subset of a given size has equal probability
- Prerequisite
- A complete sampling frame listing all population units
- Statistical role
- Reference design for most inference formulas
Common questions
Why is true simple random sampling hard to achieve in forensic surveys?+
It requires a complete, accurate list of every unit in the population before any unit can be drawn, which is often unavailable in casework or field settings, so practitioners frequently substitute stratified or systematic sampling and adjust the statistics accordingly.
How does simple random sampling differ from stratified sampling?+
Simple random sampling draws directly from the whole population with no grouping, while stratified sampling first divides the population into subgroups and samples within each, which can improve precision when those subgroups differ meaningfully.
Related terms
- Cluster Sampling
- A design in which the population is divided into naturally occurring groups called clusters, a random sample of clusters is selected, and...
- Sampling Bias
- A systematic distortion in an estimate caused by a selection process that does not give all units a known probability of inclusion....
- Sampling Error
- The difference between a sample statistic and the true population value, arising from the randomness of selection. It can be estimated from...
- Sampling Frame
- The list or description of all units from which the sample can be drawn. Any unit not on the frame cannot be...
- Stratified Sampling
- A sampling design that divides the population into homogeneous subgroups (strata) and samples each stratum separately. Allows the auditor to apply higher...