In research, a sample is simply the individuals that participate in a study. Below are limitations in sampling when doing research.

• A sample that is small and/or homogenous limits the ability of the results of a study to be generalized.  However, research usually needs to be done within a certain timeframe. There may not be time to analyze the data generated from a large sample size.  Thus, researchers have to make decisions (and sometimes compromises) between what is practical and what will give good data.
• Bias may result if a researcher is not blinded of a sample group.
• Time may also be a factor in inaccurate data gathered from a sample. Such may occur if individuals within a sample were being measured to determine the likelihood that proper healing will after a medical procedure. Healing may still be occurring if data is collected prematurely.
• A sampling frame rarely is a perfect representation of the entire population that is being studied or researched.