What type of study uses systematic, quantitative methods to combine results from multiple studies for a comprehensive estimate?

The correct answer is meta-analysis. This type of study is designed to systematically combine the results from multiple individual studies to provide a comprehensive overview and estimate of an effect or outcome. By using quantitative methods, meta-analysis allows researchers to integrate diverse findings, account for variability across studies, and draw more reliable conclusions than any single study could provide.

Meta-analysis involves a rigorous process where studies are selected based on specific criteria, data from these studies are extracted, and statistical techniques are employed to analyze this information collectively. This helps enhance the power of findings and allows for a clearer understanding of trends that may exist across multiple populations or interventions.

The other options do not accurately describe this process. Trend studies might analyze changes over time but do not combine results from multiple studies in the same systematic way. Experimental studies focus on testing a hypothesis under controlled conditions, which does not involve the aggregation of data from other studies. Nonbiased is a term that refers to the absence of bias in research design or analysis but does not define a specific type of study that combines results from multiple sources. Thus, meta-analysis is clearly the appropriate term for the method described in the question.