How do you compare evidence from multiple studies in biostatistics and epidemiology?

1 Identify the research question

The first step is to define the research question that you want to answer by comparing evidence from multiple studies. The research question should be clear, specific, and relevant to the topic of interest. For example, you might want to compare the effectiveness of different treatments for a certain disease, or the association between a risk factor and an outcome. The research question will guide your selection and evaluation of the studies.

2 Search and select the studies

The next step is to search for and select the studies that are relevant to your research question. You can use databases, journals, websites, or other sources to find studies that have similar or related objectives, methods, populations, and outcomes. You should apply some criteria to filter out the studies that are not suitable for your comparison, such as quality, validity, reliability, and consistency. You should also document your search and selection process for transparency and reproducibility.

3 Extract and summarize the data

The third step is to extract and summarize the data from the selected studies. You should use a standardized form or table to record the key information from each study, such as authors, year, design, sample size, variables, results, and conclusions. You should also calculate some summary statistics, such as mean, standard deviation, median, range, or confidence intervals, to describe the data. You should check the data for accuracy and completeness before proceeding to the next step.

4 Compare and synthesize the evidence

The fourth step is to compare and synthesize the evidence from the selected studies. You should look for similarities and differences in the data, results, and conclusions across the studies. You should also consider the sources of variation and heterogeneity, such as methodological, clinical, or statistical factors, that might affect the comparison. You should use appropriate methods and tools, such as meta-analysis, systematic review, or narrative synthesis, to combine and interpret the evidence.

5 Assess the quality and strength of the evidence

The fifth step is to assess the quality and strength of the evidence from the selected studies. You should use some criteria or scales to evaluate the quality of each study, such as risk of bias, validity, reliability, and applicability. You should also use some frameworks or guidelines to grade the strength of the evidence, such as GRADE, SORT, or CEBM, based on the quality, consistency, precision, and directness of the evidence.

6 Communicate and apply the evidence

The final step is to communicate and apply the evidence from the selected studies. You should write a clear and concise report or article that summarizes your research question, methods, results, and conclusions. You should also include some limitations, implications, and recommendations for future research or practice. You should use appropriate formats, styles, and references to present your evidence. You should also share your evidence with your peers, stakeholders, or audiences, and use it to inform your decisions or actions.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?