Stratified sampling

Definition

Stratified sampling is a method of sampling that involves dividing a population into distinct subgroups, known as strata, and then randomly selecting samples from each stratum. This technique ensures that each subgroup is adequately represented in the sample, which can lead to more accurate and reliable results. By using stratified sampling, researchers can capture the diversity within a population, making it especially useful for studies that aim to compare different segments.

5 Must Know Facts For Your Next Test

1. Stratified sampling can enhance the precision of estimates by ensuring that each subgroup is adequately represented in the final sample.
2. This method is particularly effective in heterogeneous populations where certain characteristics vary significantly among different subgroups.
3. Researchers must carefully define strata based on relevant characteristics before selecting samples to ensure meaningful comparisons.
4. Stratified sampling can be either proportionate or disproportionate, depending on whether the sample sizes from each stratum reflect their proportions in the population.
5. It is crucial to use random selection within each stratum to maintain the integrity of the sampling process and avoid bias.

Review Questions

• How does stratified sampling improve the accuracy of research findings?
  • Stratified sampling improves accuracy by ensuring that all relevant subgroups within a population are represented in the sample. By dividing the population into strata based on shared characteristics and then randomly selecting participants from each stratum, researchers can reduce sampling bias. This approach allows for more precise estimates and enhances the validity of comparisons across different segments of the population.
• Compare and contrast stratified sampling with random sampling in terms of their effectiveness for diverse populations.
  • While random sampling gives every individual in a population an equal chance of selection, it may not effectively capture all subgroups within diverse populations. Stratified sampling, on the other hand, specifically targets these subgroups by ensuring representation from each stratum. This makes stratified sampling generally more effective for studies involving heterogeneous populations, as it allows researchers to analyze differences and similarities among distinct segments.
• Evaluate the impact of poorly defined strata on the outcomes of a study utilizing stratified sampling.
  • Poorly defined strata can significantly compromise the outcomes of a study using stratified sampling by leading to misrepresentation of certain groups. If strata are not clearly established based on relevant characteristics, the resulting sample may fail to accurately reflect the diversity within the population. This can skew results, render findings unreliable, and ultimately affect conclusions drawn from the research. Hence, careful consideration and clear definitions of strata are essential for successful stratified sampling.

Related terms

Population: The entire group of individuals or instances about whom we hope to learn, from which samples are drawn.

Sampling Error: The difference between the sample statistic and the actual population parameter, often due to random chance in sample selection.

Random Sampling: A method of sampling where every member of the population has an equal chance of being selected, reducing bias in the sample.