Suppose you are designing an experiment to test the effects of nicotine on the heart rate of rats. what are the disadvantages of having too small of a sample size (i. e. testing on too few rats) ? what are the disadvantages of having too large a sample size (i. e. testing on too many rats) ?

If you are performing an experiment, the goal is usually to get a representative view of a result in a certain target or population. Because of practical reasons (too big, too expensive, taking too much time, ...) it is often difficult to work on the whole population. In this case, a sample is used. This is a selection of the population, chosen to reflect the best possible population.

It is very important to use a correct size for your sample. If it is too big, it can create unnecessary costs and delays. When your sample is too small, the results are not statistically significant and no reliable conclusion can be drawn.