Table 2 Pooled fixed effects (standardised mean differences) by year of publication, study design, platform, time interval between administrations, age, sample size and publication type for the 307 available standardised mean differences

 2007

98

0.051 (0.040–0.062)

 2008–2010

76

0.022 (0.011–0.033)

 2011

69

0.031 (0.020–0.041)

 2012–2013

64

0.047 (0.035–0.058)

p < 0.001

 2007–2010

174

0.036 (0.028–0.043)

2011–2013

133

0.038 (0.030–0.045)

p = 0.709

 Randomized cross over

232

0.030 (0.023–0.036)

 Non–randomised crossover

12

0.033 (−0.003–0.068)

 Within–patient study

40

0.099 (0.077–0.122)

 Parallel group study

23

0.046 (0.033–0.060)

p < 0.001

 Randomised^a

256

0.034 (0.028–0.040)

 Not randomised

51

0.065 (0.046–0.084)

p = 0.002

 Paper vs IVRS

40

0.053 (0.038–0.069)

 Paper vs PDA

60

0.106 (0.070–0.142)

 Paper vs Web/PC

152

0.038 (0.031–0.045)

 Paper vs Tablet/touch screen

51

0.020 (0.009–0.031)

 Tablet/touch vs Web/PC

4

0.044 (−0.113–0.221)

p < 0.001

 0 (<1 day)

159

0.036 (0.028–0.044)

 1 (1–5 days)

61

0.034 (0.024–0.044)

 2 (6–14 days)

50

0.036 (0.022–0.051)

 3 (15+ days)

37

0.051 (0.032–0.069)

p = 0.460

 0 (<1 day)

159

0.036 (0.028–0.044)

 1 (1–9 days)

85

0.033 (0.025–0.041)

 2 (10+ days)

63

0.055 (0.038–0.072)

p = 0.077

 <28 years

86

0.064 (0.051–0.077)

 28–46.9 years

37

0.019 (0.009–0.029)

 47–55.9 years

51

0.028 (0.017–0.039)

 56+ years

125

0.049 (0.038–0.061)

p < 0.001

 ≤56

114

0.071 (0.055–0.087)

 57–116

94

0.024 (0.014–0.035)

 >116

99

0.036 (0.029–0.043)

p < 0.001

 Abstract/poster

3

0.071 (−0.016–0.158)

 Full text publication

304

0.037 (0.031–0.042)

p = 0.436