Representative Sample

What Is a Representative Sample?

A representative sample is a subset of a population that seeks to accurately reflect the characteristics of the larger group. For example, a classroom of 30 students with 15 males and 15 females could generate a representative sample that might include six students: three males and three females. Samples are useful in statistical analysis when population sizes are large because they contain smaller, manageable versions of the larger group.

Understanding Representative Sample

Sampling is used in statistical analysis methodologies to gain insights and observations about a population group. Statisticians can use a variety of sampling methods to build samples that seek to meet the goals of their research studies. Representative samples are one type of sampling method. This method uses stratified random sampling to help identify its components. Other methods can include random sampling and systematic sampling.

A representative sample seeks to choose components that match with key characteristics in the entire population being examined.

Statisticians can choose the representative characteristics that they feel best meet their research goals. Typically, representative sample characteristics are focused on demographic categories. Some examples of key characteristics can include sex, age, education level, socioeconomic status, and marital status. Generally, the larger the population being examined, the more characteristics that may arise for consideration.

Types of Sampling Methods

Choosing a sampling method can depend on a variety of factors. Representative samples are usually an ideal choice for sampling analysis because they are expected to yield insights and observations that closely align with the entire population group.

When a sample is not representative, it can be known as a random sample. While random sampling is a simplified sampling approach, it comes with a higher risk of sampling error which can potentially lead to incorrect results or strategies that can be costly. Random sampling can choose its components completely at random, such as choosing names randomly from a list. Using the classroom example again, a random sample could include six male students.

Systematic sampling is another type of sampling method that seeks to systemize its components. This type of sampling may include choosing every fifth person from a population list to gather a sample. While this method takes a systematic approach, it is still likely to result in a random sample.

Stratified Random Sampling

Stratified random sampling can be an important part of the process in creating a representative sample. Stratified random sampling examines the characteristics of a population group and breaks down the population into what is known as strata. Dividing out the population by strata helps an analyst to easily choose the appropriate number of individuals from each stratum based on proportions of the population. While this method is more time consuming — and often more costly as it requires more upfront information — the information yielded is typically of higher quality.

Special Considerations

A representative sample is generally expected to yield the best collection of results. Representative samples are known for collecting results, insights, and observations that can be confidently relied on as a representation of the larger population being studied. As such, representative sampling is typically the best method for marketing or psychology studies.

While representative samples are often the sampling method of choice, they do have some barriers. Oftentimes, it is impractical in terms of time, budget, and effort to collect the data needed to build a representative sample. Using stratified random sampling, researchers must identify characteristics, divide the population into strata, and proportionally choose individuals for the representative sample.

In general, the larger the population target to be studied the more difficult representative sampling can be. This method can be especially difficult for an extremely large population such as an entire country or race. When dealing with large populations it can also be difficult to obtain the desired members for participation. For example, individuals who are too busy to participate will be under-represented in the representative sample. Understanding the pros and cons of both representative sampling and random sampling can help researchers select the best approach for their specific study.