As the sample size increases, the results become more reliable, suggests the Andrews University website. Larger sample sizes are particularly important when finding small differences in a large population, since each new sample could bring about additional variance. Statisticians aim to find an appropriate sample size that will provide accurate results.
Increasing the sample size makes the study more ethical, especially if the researcher is attempting to prove something specific. The more variance the researcher brings into the equations, the more accurate the results become.
The end goal is to reflect the population mean and to show a percentage based on that mean. Therefore, the more people in a population that a study includes, the closer the results get to reflecting the population as a whole.