Rather than using samples and following a rigid protocol(strict set of rules) to examine limited number of variables, case study methods involve an in-depth, longitudinal(over a long period of time) examination of a single instance or event: a
case. They provide a systematic way of looking at events, collecting
data, analyzing
information, and reporting the results. As a result the researcher may gain a sharpened understanding of why the instance happened as it did, and what might become important to look at more extensively in future research. Case studies lend themselves to both generating and testing
hypotheses 
login zone
Gulf of Mexico’s Dead Zone
