| Group matching | Articles |
| One group only (15) | [143–155, 158, 166] | Number, age, gender, education (8) | [26, 37, 66, 81, 103, 115, 124, 176] | Number, age, gender (10) | [38–40, 86, 89, 90, 102, 118, 119, 173] | Number, age, education (7) | [77, 95, 98, 99, 111, 164, 165] | Age, gender, education (4) | [82, 128, 162, 168] | Number, age (18) | [42, 80, 94, 100, 108–110, 112, 120–122, 132, 134, 136–139, 172] | Number, gender (2) | [88, 142] | Number, education (3) | [58, 79, 167] | Age, gender (3) | [78, 84, 123] | Age, education (3) | [129, 169, 171] | Number (8) | [83, 87, 97, 107, 117, 135, 140, 163] | Age (12) | [41, 91, 92, 96, 113, 114, 125–127, 141, 175, 178] | Not paired or no information (19) | [85, 93, 101, 104–106, 116, 130, 131, 133, 156, 157, 159–161, 170, 174, 177, 179] |
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