In a systematized review, "coding" refers to a description of the important elements of the final set of studies. You will determine the variables or characteristics that are important to your research.
Some general characteristics might include: geographic location of study, demographics of population studied, method used, and/or the main focus of the study.
There may be additional, more specific characteristics that are relevant to your research question, such as: type of school, outcome measures, diagnosis, etc.
This information is usually gathered in a spreadsheet and presented in the results section of your paper, first as a table, then as a narrative description summarizing the characteristics of the studies.
Here's an example coding spreadsheet for the research question: In what ways do colleges support student parents that increase their retention and graduation rates?
A table presenting these important elements of your studies should be included in the results section of your paper. It might look something like this:
Table 1. Characteristics of included studies
You can include the main findings of each source in this table, or you can save the findings for a separate table.
You are familiar with synthesizing information from sources from writing your literature review. In your literature review, you synthesized information from various sources to describe the scholarly conversation about your topic.
The synthesis you do for your systematized review method is similar in that you are looking across sources to find connections, but different in that you are synthesizing the findings of the studies in order to answer your research question.
Similarly to what you did for your literature review, you can use a synthesis table to find the themes or connections among your systematized review sources to help you answer your research question. The table below is an example of what that might look like.
Table 2: Synthesis of findings from included studies
Once you've laid out the findings of the studies as they relate to your research question, you can use the narrative following the table to describe what the findings all mean together. For example, from the above table you might observe that vouchers for off-campus childcare improve outcomes for student parents, but only when they fund 80-100% of childcare costs.