Understanding Equiprobability in Sampling

The question asks for the term that describes when every unit in a population has an equal chance of being selected for a sample. This is a fundamental concept in statistical sampling.

Defining Equiprobability Selection

Equiprobability means that each individual item or unit within the entire group (the universe or population) has the exact same likelihood of being chosen.

Analyzing Sampling Methods

• Random Sampling: This is the core definition. In random sampling, every unit has an equal and independent chance of being selected. Techniques like simple random sampling, systematic sampling (with random start), stratified random sampling, and cluster sampling all fall under this umbrella and aim to maintain equiprobability at some level.
• Convenience Sampling: This method selects units that are easiest to reach. The selection is based on convenience, not equal probability. Some units have zero chance of being selected.
• Purposive Sampling: Here, the researcher handpicks units based on specific characteristics or knowledge. The selection is deliberate and not based on equal chances for all units.
• Double Sampling: This involves using information from a first sample to refine the selection of a second, more detailed sample. While the initial selection might be random, the defining feature isn't the equiprobability of the entire universe in one go.

Conclusion

Based on the definition, Random Sampling is the technique that guarantees the equiprobability of selection for every unit in the universe.

Correct Option: 1. Random Sampling