Why are repeated trials important in scientific investigations and what should you do if repeated trials give very different results?

We know that many phenomena are quite variable. The weather is not the same every day. One person does not necessarily act the same way or have the same biological features as another person. Some individuals might be typical of their species, while others might be unusual in some way. So, if you are investigating some particular phenomenon, you want to make sure that the results that you got are normal or representative results, rather than anomalous results. Even aside from the variability of nature, there is also the factor of the imperfection of scientists. Scientists can also be sloppy, and can make mistakes. You might have used the wrong chemical, mislabeled something or misread a label, and so forth. We can never simply assume that any given experiment was done correctly. So, by doing something repeatedly, we can be more confident of the result. We confirm the result by getting it more than once.

If, however, we do repeated trials and get different results, that is an interesting observation and it becomes necessary for us as scientists to find out the reason for these varying results. There is something we did not notice, something that is not the same, or something that is more unpredictable than we thought it was. Maybe we thought that all of our mice were the same, but it turns out that we are actually dealing with two different species of mice, and they have significantly different biological traits. Whatever the problem is, we have to track it down and identify it, otherwise we will never be able to understand the results of our experiment.