When a scientist begins an experiment using the scientific method, they need to ensure that every step is taken in the scientific method, to prevent errors. They must avoid disregarding the null hypothesis, ask the right questions, evaluate all data and factors of the experiment and correctly calculate the p value.
Scientists can intentionally skew the results of an experiment by performing the experiment in a way that it results in a certain answer, by ignoring or excluding certain factors. They can unintentionally skew an experiment’s results by disregarding the null hypothesis. For example, in the experiment with the rats and toluene, if a scientist assumes toluene is the cause of birth defects, and ignores other factors like environment, temperature, and treatment of the mother rats, the experiment can be skewed, and a scientist would reject the null hypothesis, which may actually be the true answer, that toluene is not the cause of the birth defects in rats.
If a scientist does not ask the right questions, an experiment’s results might become unintentionally skewed. For instance, a researcher can asks, “does toluene cause birth defects in rats”. If that researcher fails to ask “does toluene always cause birth defects in rats”, they may not see that there are certain conditions in which the rats are affected and certain conditions in which they are not (limiting factors).
If a researcher fails to use all steps of the scientific method, or fails to use a control group, the results of an experiment can be false. Any time a scientist does an experiment, they should repeat it at least once to make sure their first assumptions were correct and not just a lucky try. They must use further observation and view all aspects of the situation.
One personal bias that I bring to the analysis of environmental science is that I do not think animals should be needlessly harmed for cosmetic research or other superficial research. I think that experimentation should be as humane as possible and that the only time harm to an animal should be permissible is when that research will prevent harm to animals or people in the future.