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Table 3 The mean ratio of standard errors and 95% limits of agreement for the meta-analytic immediate level-change (top triangle, ratio calculated as column method / row method) and slope-change per month (bottom triangle, ratio calculated as row method / column method) (n = 17)

From: Comparison of statistical methods used to meta-analyse results from interrupted time series studies: an empirical study

 

Level-change

Slope-change per month

OLS ITS

Fixed MA

1.70 (0.59,4.94)

1.60 (0.37,6.90)

1.78 (0.55,5.73)

1.61 (0.37,6.99)

1.06 (0.71,1.57)

1.75 (0.63,4.85)

1.61 (0.43,6.02)

1.80 (0.61,5.32)

1.62 (0.43,6.12)

2.10 (0.61,7.22)

OLS ITS

DL + WT MA

0.94 (0.54,1.64)

1.04 (0.88,1.24)

0.94 (0.53,1.67)

0.62 (0.20,1.95)

1.03 (0.68,1.55)

0.95 (0.61,1.46)

1.06 (0.79,1.41)

0.95 (0.61,1.48)

2.29 (0.42,12.57)

1.09 (0.57,2.09)

OLS ITS

DL + HKSJ MA

1.11 (0.68,1.82)

1.00 (0.98,1.02)

0.66 (0.14,3.11)

1.09 (0.51,2.35)

1.01 (0.62,1.63)

1.13 (0.60,2.11)

1.01 (0.63,1.63)

2.42 (0.51,11.52)

1.15 (0.70,1.90)

1.06 (0.71,1.58)

OLS ITS

REML + WT MA

0.90 (0.55,1.48)

0.59 (0.17,2.11)

0.98 (0.59,1.63)

0.91 (0.61,1.36)

1.01 (0.75,1.37)

0.91 (0.61,1.36)

2.40 (0.40,14.49)

1.14 (0.52,2.49)

1.05 (0.89,1.24)

0.99 (0.62,1.56)

OLS ITS

REML + HKSJ MA

0.66 (0.14,3.13)

1.09 (0.50,2.37)

1.00 (0.62,1.63)

1.12 (0.60,2.11)

1.01 (0.62,1.63)

1.20 (0.80,1.79)

0.57 (0.17,1.95)

0.52 (0.09,2.94)

0.49 (0.10,2.35)

0.50 (0.08,3.08)

REML ITS

Fixed MA

1.65 (0.56,4.90)

1.52 (0.38,6.15)

1.70 (0.53,5.45)

1.53 (0.37,6.28)

2.31 (0.78,6.82)

1.10 (0.72,1.68)

1.01 (0.42,2.40)

0.95 (0.49,1.87)

0.96 (0.37,2.50)

1.93 (0.66,5.62)

REML ITS

DL + WT MA

0.92 (0.56,1.51)

1.03 (0.78,1.37)

0.93 (0.56,1.54)

2.40 (0.46,12.52)

1.14 (0.53,2.46)

1.05 (0.71,1.55)

0.99 (0.57,1.70)

1.00 (0.69,1.46)

2.00 (0.37,10.96)

1.04 (0.46,2.34)

REML ITS

DL + HKSJ MA

1.12 (0.78,1.59)

1.01 (0.98,1.03)

2.58 (0.58,11.57)

1.23 (0.55,2.73)

1.13 (0.50,2.53)

1.06 (0.58,1.96)

1.08 (0.48,2.44)

2.15 (0.47,9.88)

1.12 (0.60,2.08)

1.08 (0.57,2.02)

REML ITS

REML + WT MA

0.90 (0.63,1.29)

2.44 (0.42,14.23)

1.16 (0.46,2.92)

1.07 (0.63,1.80)

1.01 (0.53,1.93)

1.02 (0.64,1.63)

2.04 (0.33,12.60)

1.06 (0.42,2.67)

1.02 (0.84,1.24)

0.95 (0.51,1.75)

REML ITS

REML + HKSJ MA

  1. For example, on average the standard error of the meta-analytic level-change yielded by REML ITS analysis with fixed effect meta-analysis was 6% higher than the standard error yielded by OLS ITS analysis with fixed effect meta-analysis (column 6, row 1), while the standard error of the meta-analytic slope-change per month yielded by REML ITS analysis with fixed effect meta-analysis was, on average, 20% higher than the standard error yielded by OLS ITS analysis with fixed effect meta-analysis (column 1, row 6)
  2. DL DerSimonian and Laird, HKSJ Hartung-Knapp/Sidik-Jonkman, ITS interrupted time series, MA meta-analysis, OLS ordinary least squares, REML restricted maximum likelihood, WT Wald-type
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BMC Medical Research Methodology

ISSN: 1471-2288

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