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. You will want to have a column for the intervention that you identified in your PICOS, which will describe the specific intervention for each study.
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
The main findings of each source in this table will be presented in the synthesis table (below), rather than the coding 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 connections among your systematized review sources to help you answer your research question. But instead of entering all the findings from the articles and seeing what themes emerge, you will group the findings in columns by the type of intervention addressed in the studies.
One of the columns in your coding table should have been for the interventions/conditions that each study investigated. The label for that column may be something different, but it should address the "I" of your PICOS. Take the interventions listed in your coding table and determine ways to logically group them. For example, if your intervention is "programs for English Language Learners," then perhaps some of the studies address dual language immersion, some address bilingual education, and some address other types of English language acquisition. These groupings of interventions will then be the columns in your synthesis table.
Each of these groupings will have two columns in the synthesis table, one for "characteristics" and one for "findings." In the "characteristics" column, briefly describe the intervention. Even though it's already in an intervention grouping, such as "on-campus childcare" in the example below, what kind of on-campus childcare is it? Listing the characteristics of the intervention will help you see whether certain types of interventions are more effective than others.
In the "findings" column, briefly describe each study's findings as they relate to that intervention. For clarity, use complete but brief sentences with this form: X (intervention) resulted in Y (outcome). For example: "Participation in bilingual education improved graduation rates."
The table below is an example of what this might look like (if it's hard to see, open the table as a spreadsheet).
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.
If your research question doesn't seem to fit well with this model, or if you are struggling to determine the groupings of your interventions, please contact your advisor for support.