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Table 3 Estimated regression coefficients from the semiparametric models

From: Exploring the nonlinear relationship between body mass index and health-related quality of life among adults: a cross-sectional study in Shaanxi Province, China

  Men   Women
Estimate Std. Error   Estimate Std. Error
Model 1 (Adj R2 = 0.114)    Model 1 (Adj R2 = 0.141)   
Socio-demographic and physical activity    Socio-demographic and physical activity   
Intercept 1.010** 0.00521 Intercept 1.005** 0.00610
BMI Estimated with 6.753 edf, see left plot of Figure 1 BMI Estimated with 6.791 edf, see left plot of Figure 2
Age −0.0020** 0.00007 Age −0.0021** 0.00007
Marital status    Marital status   
 Unmarried(ref)    Unmarried(ref)   
 Married 0.0249** 0.00308 Married 0.0192** 0.00436
 Divorced or widowed −0.0026 0.00453 Divorced or widowed −0.0154** 0.00541
Educational attainment    Educational attainment   
 Illiteracy(ref)    Illiteracy(ref)   
 Elementary 0.0141** 0.00304 Elementary 0.0283** 0.00248
 Middle school 0.0223** 0.00305 Middle school 0.0333** 0.00261
 High school 0.0241** 0.00354 High school 0.0342** 0.00349
 University 0.0248** 0.00471 University 0.0320** 0.00478
Residential areas    Residential areas   
 Urban(ref)    Urban(ref)   
 Rural 0.0001 0.00023 Rural 0.0002 0.00024
Economic status    Economic status   
 Poorest(ref)    Poorest(ref)   
 Poorer 0.0057* 0.00251 Poorer 0.0067* 0.00265
 Middle 0.0119** 0.00254 Middle 0.0107** 0.00265
 Richer 0.0093** 0.00261 Richer 0.0061* 0.00270
 Richest 0.0126** 0.00270 Richest 0.0066* 0.00278
Physical activity    Physical activity   
 No(ref)    No(ref)   
 Yes 0.0039* 0.00216 Yes 0.0130** 0.00207
Model 2 (Adj R2 = 0.149)    Model 2 (Adj R2 = 0.188)   
Socio-demographic and physical activity    Socio-demographic and physical activity   
Intercept 0.9979** 0.00519 Intercept 0.9975** 0.00603
BMI Estimated with 6.693 edf, see right plot of Figure 1 BMI Estimated with 6.750 edf,
see right plot of Figure 2
Age −0.0016** 0.00007 Age −0.0017** 0.00007
Marital status    Marital status   
 Unmarried(ref)    Unmarried(ref)   
 Married 0.0227** 0.00305 Married 0.0144** 0.00430
 Divorced or widowed −0.0044 0.00448 Divorced or widowed −0.0181** 0.00534
Educational attainment    Educational attainment   
 Illiteracy(ref)    Illiteracy(ref)   
 Elementary 0.0154** 0.00301 Elementary 0.0276** 0.00245
 Middle school 0.0238** 0.00302 Middle school 0.0320** 0.00257
 High school 0.0265** 0.00351 High school 0.0334** 0.00344
 University 0.0268** 0.00466 University 0.0308** 0.00471
Residential areas    Residential areas   
 Urban(ref)    Urban(ref)   
 Rural −0.0001 0.00023 Rural 0.0001 0.00023
Economic status    Economic status   
 Poorest(ref)    Poorest(ref)   
 Poorer 0.0063* 0.00248 Poorer 0.0067* 0.00260
 Middle 0.0123** 0.00251 Middle 0.0104** 0.00261
 Richer 0.0096** 0.00258 Richer 0.0058* 0.00266
 Richest 0.0130** 0.00267 Richest 0.0061* 0.00274
Physical activity    Physical activity   
 No(ref)    No(ref)   
 Yes 0.0071** 0.00214 Yes 0.0147** 0.00205
Co-morbidities    Co-morbidities   
 Hypertension −0.0343** 0.00261 Hypertension −0.0363** 0.00250
 Diabetes −0.0387** 0.00534 Diabetes −0.0253** 0.00523
 Heart problems −0.0574** 0.00619 Heart problems −0.0680** 0.00516
 Respiratory disease −0.0588** 0.00626 Respiratory disease −0.0340** 0.00752
 Musculoskeletal problems −0.0821** 0.00441 Musculoskeletal problems −0.0928** 0.00386
 Cancer −0.1767** 0.02517 Cancer −0.1577** 0.02098
  1. BMI Body mass index
  2. ref reference category
  3. edf effective degrees of freedom
  4. *P < 0.05; ** P < 0.01