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 a sample size (i. e., testing on too few rats) ?

The larger the sample size the fewer errors would be made. it also averages out the results. depending on what the experiment is like i. e.: how would ___ nicotine affect the heart rate of 100 rats. your prediction/hypothesis would be closer to the experiment results with a larger test number of say 1000. but with a smaller sample size its hard to accurately predict and have more consistent resulta