Table 6 Length of studies

Up to 1 week

9

[172, 203, 210, 212, 224, 229, 239, 266, 270]

1–2 weeks

27

[50, 170, 174, 178, 182, 189, 192, 194, 198, 202, 215, 218, 220, 223, 228, 234, 235, 237, 240, 249, 254, 260–265]

2–3 weeks

36

[52, 53, 168, 169, 173, 175, 179, 180, 183–186, 190, 191, 195, 196, 199, 200, 204, 205, 209, 213, 217, 225, 226, 230, 232, 233, 236, 246, 250, 256, 258, 269, 271]

3–4 weeks

15

[51, 176, 181, 188, 193, 201, 211, 216, 219, 221, 241, 251, 253, 255, 257]

4–5 weeks

7

[171, 177, 206, 214, 231, 259, 267]

5–6 weeks

10

[48, 187, 208, 222, 238, 244, 247, 248, 252, 268]

6–7 weeks

1

[207]

7–8 weeks

1

[197]

8–9 weeks

3

[164, 243, 245]

Not stated

1

[242]