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Table 7 Multiple linear regression with stepwise inclusion of variables (HI superregion serves as reference for other superregions)

From: The global prevalence of headache: an update, with analysis of the influences of methodological factors on prevalence estimates

Model 1: Original data set

Headache, N = 181

(5 variables)

Migraine, N = 242

(8 variables)

TTH, N = 109

(4 variables)

H15+, N = 58

(2 variables)

Whole model

F = 10.3, p < 0.001, R2 adj: 0.208

F = 13.9, p < 0.001, R2 adj: 0.299

F = 6.9, p < 0.001, R2 adj: 0.181

F = 6.6, p = 0.003, R2 adj: 0.165

Variables with significance

β standardised

SPCsqr

β standardised

SPCsqr

β standardised

SPCsqr

β standardised

SPCsqr

Year of publication

  

0.258

0.060

    

Number (ln transformed) of participants

−0.207

0.040

− 0.146

0.018

    

dMig and pMig

  

0.269

0.064

    

dTTH and pTTH

      

0.321

0.102

Health-care personnel

  

0.173

0.022

    

Sampling method

  

−0.169

0.022

    

Type of screening question

−0.307

0.090

  

−0.285

0.080

  

Number of conditions

−0.162

0.026

      

Mode of engagement

      

0.281

0.078

SSA superregion

−0.148

0.021

−0.173

0.028

−0.232

0.052

  

SEEAO superregion

−0.171

0.029

−0.136

0.018

−0.294

0.084

  

NAME superregion

  

−0.113

0.011

−0.231

0.051

  

Model 2: ln transformed dependent variable and outliers (±1.5 interquartile range) removed

Headache, N = 176

(4 variables)

Migraine, N = 238

(7 variables)

TTH, N = 103

(4 variables)

H15+, N = 57

(2 variables)

Whole model

F = 11.3 p < 0.001, R2 adj: 0.191

F = 13.6, p < 0.001, R2 adj: 0.271

F = 5.5, p < 0.001, R2adj:0.150

F = 6.5, p = 0.003, R2 adj: 0.164

Variables with significance

β standardised

SPCsqr

β standardised

SPCsqr

β standardised

SPCsqr

β standardised

SPCsqr

Year of publication

  

0.259

0.064

    

Number (ln transformed) of participants

−0.186

0.032

−0.137

0.016

  

−0.354

0.125

dMig and pMig

  

0.291

0.078

    

dTTH and pTTH

0.166

0.027

      

Health-care personnel

  

0.133

0.013

    

Sampling method

  

−0.169

0.022

    

Type of screening question

−0.277

0.072

  

−0.233

0.054

  

SEEAO superregion

  

−0.110

0.012

−0.206

0.058

−0.250

0.062

SSA superregion

−0.207

0.042

−0.180

0.031

−0.245

0.042

  

NAME superregion

    

−0.264

0.068

  
  1. R2 adj (Adjusted R2): The proportion of variability explained by the whole model (“Goodness of fit”), adjusted for overestimation caused by the number of effects
  2. β-standardised: The direction and strength of its correlation with the dependent prevalence variable
  3. SPCsqr: the proportion of the variability explained by that variable alone