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Table 2 Values of actual risk equation relating BMI to probabilities of developing diabetes using logistic regression values from the National Population Health Survey (NPHS) 10-year follow-up cohort and values achieved from the simulation model

From: The influence of measurement error on calibration, discrimination, and overall estimation of a risk prediction model

 

Males – NPHS data (N = 9,177)

Males – Simulation (N = 9,177)

Variable

Coefficient

Standard error

P-value

Coefficient

Standard error

P-value

BMI

0.4202

0.0383

< 0.0001

0.4263

0.0111

< 0.0001

BMI2

−0.00437

0.000618

< 0.0001

−0.00448

0.001049

< 0.0001

Intercept

−10.4034

  

−10.4897

  

Model properties

      

Calibration (χ2 HL)

χ2 HL = 5.67, p-value = 0.6841

χ2 HL =9.951, p-value = 0.3689

Discrimination (C-statistic)

C = 0.677

C = 0.686

 

Females – NPHS data (N = 10,618)

Females – Simulation (N = 10,618)

Variable

Coefficient

Standard error

P-value

Coefficient

Standard error

P-value

BMI

0.4565

0.0554

< 0.0001

0.4593

0.0779

< 0.0001

BMI2

−0.00509

0.00091

< 0.0001

−0.00514

0.00141

< 0.0001

Intercept

−10.8967

  

−10.5899

  

Model properties

      

Calibration (χ2 HL)

χ2 HL = 9.33, p-value = 0.3153

χ2 HL = 10.466, p-value = 0.3356

Discrimination (C-statistic)

C = 0.726

C = 0.718