Statistical Sampling


Statistics is the science of data that are used to collect a representative sample from an unknown target population, to summarize the sample information, and to understand the unknown population using the collected sample data.

            How can we be sure the sample we collect is a reasonably representative sample of the population? One way is by “Random Sampling.” Through a properly designed random process, we will be able to assure the sample is a representative sample. There are two important strategies to make sure the sample is representative. The first strategy is to take a large sample. If we take a very large sample, the sample data will be close to the population. Hence, there is a higher chance that the sample is a representative sample. In real situations, usually due to the time and cost limitations, we are not allowed to take a very large sample, as the population could be many millions.

            The second strategy is a technique known as randomization and stratification.  Randomization means that every subject in the population has equal opportunity to be chosen. This technique is one of the most important statistical principles in selecting a sample. The sample which is selected randomly is named a random sample. What is stratification? Imagine that you are interested in finding out a university students’ views about an issue. You may decide to survey 1000 randomly selected students from the university. However, since there are different grades, you may choose randomly 200 students from each grade, including graduate student level. The grade level is called a stratum. This sampling technique is called stratification. It is a method to increase the precision and reliability of the sample data.

How does sampling improve quality?

            After collecting the sample and analyzing the collected data using appropriate statistical methods, the results should be summarized.The summarized results should be used as the inference to explain the processes with regard to possible causes and look for ways to reduce problems.

            Finally, implement the changes on the process and continue data collection for further quality improvement. So, as you can see, random sampling (statistical sampling) is an essential part in the process of compliance with regulations and useful in improving quality at your organization.

            Looking for assistance with statistical analyses, or statistical expertise support with specific projects? Get in touch with EMMA International to speak with one of our statisticians! The EMMA team is here to provide you and your organization with all the regulatory affairs and quality management skills necessary to ensure your organization’s success. Call EMMA at (248)-987-4497 or email us at to learn more!

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