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 samplingstratified 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 one example of representative sampling is the american community survey an annual study of the nation s key demographic characteristics in order to ensure a representative sample the census bureau stratifies the population according to county living situation and other demographic features this ensures that the sampled population is an accurate snapshot of the population as a whole 1special considerationsa 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 