Final answer:
Systematic reviews are classified as secondary research, which summarizes and analyzes existing data collected by other researchers.
Step-by-step explanation:
Summaries of studies by others, such as systematic reviews, fall under the category of secondary research. This type of research involves the aggregation, analysis, and synthesis of information that has been collected by other researchers. This is different from primary research, which involves collecting new data through methods like surveys, experiments, or observations. Meta-analysis is also part of secondary research, but it is more specific and involves a statistical approach to combine the results of multiple studies to identify patterns, relationships, or effects that might not be apparent in a single study. Systematic reviews do not present original research but critically assess and compile existing research on a topic, offering valuable overviews and insights. Secondary research plays a crucial role in adding context and depth to a research topic and is essential for constructing a comprehensive understanding of the subject matter.