Answer:
Sampling error
Step-by-step explanation:
Dr. Sun is bound to have sampling error affect the result of his study. This is because sampling error in research is said to occur when a researcher just takes a random sample, usually a small number of the population of the study and chooses to study this sample rather than observing every subject that makes up the population. Researchers tend to use small number of a population when the population is large and this becomes the best option, thus making it difficult to avoid sampling error.