A systematic review is a referred to as a detailed, systematic and transparent means of gathering, appraising and synthesizing evidence to answer a well-defined question. The hallmark of systematic reviews is that they seek to reduce bias at all stages of the review process and strive to gain reliable answers to probable research-oriented questions through the means of summarizing and collecting all the available valid proofs deemed to be empirical as they align with the previously stated eligible criterion (Gopalakrishnan, 2013). This type of review is often written by a panel of experts after reviewing all the information from both published and unpublished studies, which distinguishes it from traditional literature reviews that typically examine a much smaller set of research evidence and present it from a single authors perspective.
A meta-analysis is a statistical procedure for combining numerical data from multiple separate studies. A meta-analysis should only ever be conducted in the context of a systematic review. The aim of a meta-analysis is to derive a conclusion with increased power and accuracy than what could not be able to achieve in individual studies. A meta-analysis is a systematic study in which therapeutic effectiveness is measured by calculating the weighted pooled estimate for treatments in at least two different research.
Basically a systematic review is a method used to describe trends in the research field by calculating how many studies have used certain research methodologies whereas a meta-analysis combines results from those studies in a new statistical framework to test hypotheses. Both methods can be used together, which is advantageous. However, well planned the systematic review or meta-analysis is, if the quality of evidence in the studies is low, the quality of the meta-analysis decreases and incorrect results can be obtained.
Gopalakrishnan, S., & Ganeshkumar, P. (2013). Systematic Reviews and Meta-analysis: Understanding the Best Evidence in Primary Healthcare. Journal of family medicine and primary care, 2(1), 9“14. https://doi.org/10.4103/2249-4863.109934
 Ahn, E., & Kang, H. (2018). Introduction to systematic review and meta-analysis. Korean journal of anesthesiology, 71(2), 103“112. https://doi.org/10.4097/kjae.2018.71.2.103

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Quantitative and Qualitative methods are both used to evaluate evidence. Qualitative research focuses in understanding a research query as a humanistic or idealistic approach (Pathak et al., 2013). Though quantitative approach is a more reliable method as it is based upon numeric and methods that can be made objectively and propagated by other researchers (Pathak et al., 2013). Qualitative method is used to understand people’s beliefs, experiences, attitudes, behavior, and interactions (Pathak et al., 2013). It generates non-numerical data (Pathak et al., 2013). When combined with quantitative measures, qualitative study can give a better understanding of health-related issues (Pathak et al., 2013). The perspectives in clinical research should highlight advances in qualitative research as well, to optimize quality and utility of this method of research (Pathak et al., 2013). Qualitative research gives voice to the participants in the study, it permits the participants to share their experiences of the effects of the drug of interest. This can open our eyes to new aspects of the study and help modify the design of the clinical trial (Pathak et al., 2013). Qualitative study enhances the involvement of everyone related to the study, the researcher works on the social parameters in addition to the quantitative measures in the study. The subjects also have an empowering experience in the study (Pathak et al., 2013). They have an active role in the study and can voice their individual benefits and harms of the study, as well as, with qualitative methods, the relationship between the researcher and the participant is often less formal than in quantitative research (Pathak et al., 2013).
Pathak, V., Jena, B., & Kalra, S. (2013). Qualitative research. Perspectives in clinical research, 4(3), 192. https://doi.org/10.4103/2229-3485.115389