The high out put alternator isn ' t part of the Big 3 , actually , 99 % of the time , the Big 3 is required to put in a high output alternator as the stock wiring cannot handle the output of a high output alternator . The Big 3 , sometimes also called the Big 4 , is when you upgrade the main electrical cables in your car . These include but are not limited to your engine block ground , battery ground , alternator ground , battery charging cable , etc . <| sep |> Scientists usually prove causation as opposed to correlation by performing an experimental intervention and checking whether the outcome agrees with prediction . In some fields , like political science or climate science , it isn ' t possible to perform such experiments e . g . try overthrowing a statistically significant number of democratically elected governments ! If one requires causal experiments , neither climate nor politics could be studied scientifically . However , our experience shows that there ' s another way to arrive at scientific understanding . Briefly , one builds a set predictive models hypotheses , then collects new data and checks which model best predicts the results . These measurements can occur in the future e . g . ongoing monitoring of climate , or can relate to the past e . g . predicting a new detail about past chemical concentrations , then measuring it from ice core data . Even though individual scientists can ' t causally alter the environment , they can still use this method to learn which models are most likely to be true . Some people choose to believe the results of climate science not because they represent absolute apriori truth , but because they represent a disciplined statistical best guess at how the world works . Since the climate models predict very bad things will happen if the atmosphere contains too many greenhouse gases , some people think it ' s very important to avert this risk . I hope that ' s a clear and accurate description of how other people might think differently from what I understood in your comment ? Not meaning to contradict , being able to recognize when a study is correlative is very important .