Identify the type of observational study.
Researchers plan to collect data by interviewing patients who have cardiac by-pass surgery at several local hospitals beginning in January 2014.
Cross-sectional
Retrospective
Prospective
None of these
The type of observational study described is prospective.
To identify the type of observational study, we need to consider the timing of data collection and the directionality of the study.
In this scenario, the researchers plan to collect data by interviewing patients who have cardiac by-pass surgery at several local hospitals starting in January 2014. This means that the data collection will happen in the future and will follow patients over time. This corresponds to the definition of a prospective study, which is an observational study where data is collected moving forward in time.
Cross-sectional studies collect data at one point in time and do not follow patients over time. Retrospective studies look back at past data or events. Neither of these descriptions match the scenario given. Therefore, the correct answer is prospective.