What is the difference between random sampling and random assignment? Discuss what is required regarding each, and why they are important. Consider some of the seminal experiments in the history of the field, such as Stanley Milgram’s experiment on authority and Philip Zimbardo’s prison experiment. Were they based upon random samples? Were subjects randomly assigned to groups? Why would this be important in terms of how we interpret the results of each study?
A note: Please focus on the methodology, not the ethics of the studies.
Some resources you may want to consult:
Khan Academy on Milgram’s study
Discussion of Milgram’s Experiment
Examination of Milgram’s study

In 175 words:
The primary issue with correlation is that, although we may perceive that there is a relationship between two variables, there could be many explanations and the one we choose could be only partially accurate or even completely inaccurate. We might also incorrectly view one variable as causing the other, when it might be the opposite. As we do not have complete control over the situation, we cannot truly determine the reasons/causes/explanations for the observed relationship.
Correlations are sometimes misinterpreted as causation, at times with negative impacts, such as regarding Autism and vaccinations. 
TED Talk by Wendy Chung on Autism
Correlations can also provide intriguing and valuable information, though not definite answers. They just help to point us in the direction of where further study is needed.
Readings that explore real world examples of correlation vs. causation:
Khan Academy on Correlation vs. Causation
Psychology Today on Correlation vs. Causation
Does eating sour cream cause bicycle accidents?
Share your own observations and examples of recent news reports that link two variables or events, and report a cause and effect scenario, but cannot reflect true causation. Describe what is meant by a positive vs. negative correlation and provide examples.