Why Scientist redo their experiment?

In an experiment, there are many variables (things that can't be controlled). For an accurate result, experiments must be done many times over to so that a pattern can be seen, giving scientists an idea of what the result is. For example, if you tested how music affected plant growth, and tested it once, if the plant died because of other causes, it could seem like the music affected the plant. By doing the experiment many times and seeing no affect on the majority of the plants, the scientists would see that music has no affect on plant growth. Scientists redoing experiments is to ensure that the results are credible.