Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Representative sampling and random sampling ...

Melissa Horton is a financial literacy professional. She has 10+ years of experience in the financial services and planning industry. Robert Kelly is managing director of XTS Energy LLC, and has more ...

Sampling is the process of creating a small unbiased population to be used in a test or experiment. The sample removes the impractical idea of surveying everyone in a market or a population. Random ...

Consider the example in the section "Stratified Sampling". The study population is a junior high school with a total of 4,000 students in grades 7, 8, and 9. Researchers want to know how much these ...

This example uses the Customers data set from the section "Getting Started". The data set Customers contains an Internet service provider's current subscribers, and the service provider wants to ...

Systematic sampling means testing a hypothesis by taking several equally spaced items from a larger list, eg selecting the tenth, 20th and 30th visitor to a theme park. This can be particularly useful ...