Sampling Methods and Advantages

Sampling

• Sampling is a procedure to gather information from a portion of a population, not the entire group.

Advantages of Sampling

• Lower cost compared to studying the whole population.
• Saves time.
• Allows for more in-depth and accurate investigations.
• Eliminates bias.

Precautions in Sampling

• Samples must be well-chosen and representative of the larger population.
• Samples should be large enough to minimize variations.
• Samples need adequate coverage to avoid bias.

Methods of Sampling

Non-probability Sampling

• Purposive Samples: Samples chosen based on researcher judgment. Results can't be generalized to the whole population.
• Quota Samples: Used for public opinion surveys. Not useful in public health or clinical practice.

Probability Sampling (Random Sampling)

• Every unit in the population has an equal chance of being selected.
• Allows for generalization to the larger population. This method is recommended.

Types of Random Samples

• Simple Random Sample
• Systematic Random Sample
• Stratified Random Sample
• Cluster Sample
• Multistage Random Sample

Simple Random Sample

• Create a sampling frame (a list of all units).
• Determine the sample size.
• Randomly select sample units using random number tables or computer programs.
• Useful for homogenous populations.

Systematic Random Sample

• Create a list of all sampling units.
• Determine a sampling interval (e.g., every 10th).
• Randomly select a starting point.
• Select every nth unit after the starting point.
• Often easier than simple random sampling.

Stratified Random Sample

• Divide the population into strata (groups) based on a characteristic.
• Perform simple random sampling within each stratum.
• Useful for heterogeneous populations.

Cluster Sample

• Sampling units are groups (clusters) instead of individuals (e.g., city blocks).
• Simpler to study populations spread over large areas.
• Useful for investigating people in small areas.

Multistage Sample

• Used when populations are distributed geographically.
• Sampling is done in stages (e.g., states, districts, villages, households).
• Random samples are selected at each stage.

This quiz covers the concepts of sampling, its advantages, and precautions. It discusses both non-probability and probability sampling methods, including their implications for research accuracy and generalization. Test your knowledge on how to effectively gather information from populations!