Figure 1
The flowchart begins at the top with a box labeled “Identification of search string”, followed by a downward arrow to another box labeled “Piloting the search string on databases”. Another downward arrow leads to a box labeled “Applying the search string”. From this box, three arrows branch into three horizontally arranged cylinder-shaped boxes labeled from left to right as “A C M Digital Library (218 papers)”, “Web of Science (291 papers)”, and “L I S T A (79 papers)”. From “A C M Digital Library (218 papers)”, an arrow leads down to a box labeled “20 papers”, then another arrow leads down to “13 papers”, and finally another arrow leads down to “13 papers”. From “Web of Science (291 papers)”, an arrow leads down to “30 papers”, another downward arrow leads to “10 papers”, and the final downward arrow leads to “6 papers”. From “L I S TA (79 papers)”, an arrow leads down to “12 papers”, from which another downward arrow leads to “2 papers”, and the final downward arrow leads to “2 papers”. Three individual horizontal dashed lines point from the boxes below “L I S T A” cylinder to corresponding horizontally arranged boxes on the right. From “12 papers”, the line leads to “Exclusion criteria on the basis of title, abstract and keywords”. From “2 papers”, the line leads to “Exclusion criteria on the basis of duplicates and papers not available”. From “2 papers”, the line leads to “Exclusion criteria on the basis of full reading”. At the bottom center, a box spanning all three database branches reads “Primary studies 21”.Criteria for the selection of research papers