Many people, scientists included, make incorrect judgments about how things work because they mis-attribute causes and effects. 
   Many fundamental advancements in science are due to a new understanding of the causative relationships being studied. Unfortunately, it is easy to mistake causation with correlation. 
Correlation is when two phenomena are observed simultaneously or in sequence, sometimes repeatedly, but without any proposed mechanism to assert causation, or responsibility of one event for the other.
Without a good deal of scientific testing, there is difficulty sometimes to establish the real, causal nature of the way certain things work, leading many people to come to erroneous conclusions.
It is important in everyday life and in scientific research to understand correlation does not imply causation. 
One way to emphasize this is by looking at examples of correlated events with a third event which is the actual cause of the two results in question. 
A good example put forth by Carl Sagan in his TV show “Cosmos” is pulsars, regularly pulsing stars that emit unwavering radio signals multiple times a second. 
An argument could go like this: “Intelligent humans can create regularly pulsing radio signals, I see a regularly pulsing radio signal in space and, therefore, there is an intelligent being right there.” 
But that line of reasoning is flawed, as scientists have determined it is actually a type of neutron star that rotates rapidly on its axis, causing the pulsating radio signal that we see. 
A famous example to help prove correlation does not necessitate causation is the Church of Pastafarianism’s facetious claim that “Piracy has decreased, and the average global temperature has increased; therefore, the decrease of piracy is responsible for global warming.” Scientists know increasing temperatures are due to physical effects like the sun’s cycles and the greenhouse effect, entirely unrelated to piracy.
Scientists often employ clever tricks to separate correlation from causation, such as using control experiments and placebo testing. 
In pharmaceutical trials, the drug in question is given to half the participants while a plain sugar pill (called a placebo) is given to the other half and the results are gathered. 
If the drug has any effects beyond the psychological benefit of thinking you are being given a functional pill (called the placebo effect), then the researchers can conclude something in their drug worked.
 If a scientist were to only look at his or her experiment without taking into consideration outside variables, then what he or she thought they were discovering could be completely wrong. 
As pointed out by Carl Sagan in “Cosmos,” Aristotle is a wonderful example.
He noticed a rock falls to the ground faster than a feather, andso he determined it must be because the rock is heavier than the feather, concluding heavy things must fall more quickly than light things. But this is wrong, feathers and rocks fall at the same speed in the absence of air resistance. 
Galileo approached this correctly; taking two differently weighted objects, a large and a small cannon ball, and dropping them from the leaning tower of Pisa. 
Galileo correctly determined all things accelerate at the same speed under the influence of gravity, and he actually got pretty close to developing Newtonian mechanics, supplying Newton with the groundwork to do it instead. 
Understanding appearances can be deceiving is important because many decisions we make day to day are governed by our immediate reactions to what appears to be causing what goes on. 
Without knowledge of the real workings and a healthy sense of doubt and curiosity it is easy to be get it wrong and never know a decision is based off an erroneous assumption.