Prueba de colinealidad

Luis Ernesto Juárez Linares

19 de Mayo de 2019

Cargar datos

library(stargazer)
library(haven)
hprice1 <- read_dta("C:/Users/luisn/Downloads/hprice1.dta")
head(hprice1,n=6)
## # A tibble: 6 x 10
##   price assess bdrms lotsize sqrft colonial lprice lassess llotsize lsqrft
##   <dbl>  <dbl> <dbl>   <dbl> <dbl>    <dbl>  <dbl>   <dbl>    <dbl>  <dbl>
## 1  300    349.     4    6126  2438        1   5.70    5.86     8.72   7.80
## 2  370    352.     3    9903  2076        1   5.91    5.86     9.20   7.64
## 3  191    218.     3    5200  1374        0   5.25    5.38     8.56   7.23
## 4  195    232.     3    4600  1448        1   5.27    5.45     8.43   7.28
## 5  373    319.     4    6095  2514        1   5.92    5.77     8.72   7.83
## 6  466.   414.     5    8566  2754        1   6.14    6.03     9.06   7.92

Estimacion del modelo

modelo_estimado<- lm(price~assess+bdrms+lotsize+colonial+llotsize,data = hprice1)
stargazer(modelo_estimado,type = "text",tixtle = "modelo estimado")
## 
## ===============================================
##                         Dependent variable:    
##                     ---------------------------
##                                price           
## -----------------------------------------------
## assess                       0.940***          
##                               (0.072)          
##                                                
## bdrms                          8.620           
##                               (6.791)          
##                                                
## lotsize                        0.001           
##                               (0.001)          
##                                                
## colonial                      10.031           
##                              (10.580)          
##                                                
## llotsize                      -13.357          
##                              (17.813)          
##                                                
## Constant                      68.090           
##                              (146.133)         
##                                                
## -----------------------------------------------
## Observations                    88             
## R2                             0.832           
## Adjusted R2                    0.822           
## Residual Std. Error      43.364 (df = 82)      
## F Statistic           81.224*** (df = 5; 82)   
## ===============================================
## Note:               *p<0.1; **p<0.05; ***p<0.01
## 
## ===============
## modelo estimado
## ---------------

Carlcular matriz \(|X^T X|\)

library(stargazer)
x_mat<- model.matrix(modelo_estimado)
stargazer(head(x_mat,n=6), type = "text")
## 
## =====================================================
##   (Intercept) assess  bdrms lotsize colonial llotsize
## -----------------------------------------------------
## 1      1      349.100   4    6,126     1      8.720  
## 2      1      351.500   3    9,903     1      9.201  
## 3      1      217.700   3    5,200     0      8.556  
## 4      1      231.800   3    4,600     1      8.434  
## 5      1      319.100   4    6,095     1      8.715  
## 6      1      414.500   5    8,566     1      9.056  
## -----------------------------------------------------
xx_mat<- t(x_mat)%*%x_mat
stargazer(xx_mat, type = "text")
## 
## ============================================================================================
##             (Intercept)     assess         bdrms        lotsize      colonial    llotsize   
## --------------------------------------------------------------------------------------------
## (Intercept)     88        27,784.800        314         793,748         61        783.649   
## assess      27,784.800   9,563,053.000  102,507.500 278,300,049.000 19,578.900  250,005.600 
## bdrms           314       102,507.500      1,182       2,933,767       228       2,802.953  
## lotsize       793,748   278,300,049.000  2,933,767  16,165,159,010   555,967   7,457,452.000
## colonial        61        19,578.900        228         555,967         61        544.060   
## llotsize      783.649     250,005.600    2,802.953   7,457,452.000   544.060     7,004.230  
## --------------------------------------------------------------------------------------------

Normalizacion de \(|X^T X|\)

sn<- solve(diag(sqrt(diag(xx_mat))))
stargazer(sn, type = "text")
## 
## ======================================
## 0.107   0      0      0      0     0  
## 0     0.0003   0      0      0     0  
## 0       0    0.029    0      0     0  
## 0       0      0   0.00001   0     0  
## 0       0      0      0    0.128   0  
## 0       0      0      0      0   0.012
## --------------------------------------

\(|X^T X|\) Normalizada

options(scipen = 999999)
xx_norm<- (sn%*%xx_mat)%*%sn
stargazer(xx_norm, type = "text")
## 
## ===================================
## 1     0.958 0.974 0.666 0.833 0.998
## 0.958   1   0.964 0.708 0.811 0.966
## 0.974 0.964   1   0.671 0.849 0.974
## 0.666 0.708 0.671   1   0.560 0.701
## 0.833 0.811 0.849 0.560   1   0.832
## 0.998 0.966 0.974 0.701 0.832   1  
## -----------------------------------

Calculo de Indice de condicion

Autovalores de \(|X^T X|\)

lambdas<- eigen(xx_norm, symmetric = TRUE)
stargazer(lambdas$values, type = "text")
## 
## ====================================
## 5.193 0.492 0.237 0.049 0.028 0.0005
## ------------------------------------

calculo de \(k(x) = \sqrt(Lmax/Lmin)\)

k<- sqrt(max(lambdas$values)/min(lambdas$values))
print(k)
## [1] 106.4903

Se observa un problema de colinealidad, ya que el valor es k>20

Obtener el Indice de condicion

library(mctest)
eigprop(x= x_mat[,-1])
## 
## Call:
## eigprop(x = x_mat[, -1])
## 
##   Eigenvalues       CI Intercept assess  bdrms lotsize colonial llotsize
## 1      5.1934   1.0000    0.0000 0.0014 0.0012  0.0037   0.0079   0.0000
## 2      0.4923   3.2479    0.0000 0.0001 0.0015  0.2963   0.0615   0.0000
## 3      0.2365   4.6860    0.0003 0.0113 0.0041  0.0322   0.8545   0.0002
## 4      0.0491  10.2888    0.0048 0.4576 0.0148  0.0101   0.0021   0.0027
## 5      0.0283  13.5505    0.0012 0.2138 0.9074  0.0093   0.0696   0.0017
## 6      0.0005 106.4903    0.9936 0.3158 0.0711  0.6484   0.0044   0.9954
## 
## ===============================
## Row 5==> bdrms, proportion 0.907364 >= 0.50 
## Row 6==> lotsize, proportion 0.648440 >= 0.50 
## Row 3==> colonial, proportion 0.854491 >= 0.50 
## Row 6==> llotsize, proportion 0.995427 >= 0.50

Normalizacion de \(|X^T X|\)

sn<- solve(diag(sqrt(diag(x_mat))))
stargazer(sn, type = "text")
## 
## ===========================
## 1   0     0     0   0   0  
## 0 0.053   0     0   0   0  
## 0   0   0.577   0   0   0  
## 0   0     0   0.015 0   0  
## 0   0     0     0   1   0  
## 0   0     0     0   0 0.332
## ---------------------------
xx_norm<- (sn%*%xx_mat)%*%sn
stargazer(xx_norm, type = "text")
## 
## ====================================================================
## 88          1,481.988   181.288    11,703.180      61      260.414  
## 1,481.988  27,206.410  3,156.693   218,862.700  1,044.301 4,431.284 
## 181.288     3,156.693     394      24,973.880    131.636   537.771  
## 11,703.180 218,862.700 24,973.880 3,514,165.000 8,197.286 36,538.780
## 61          1,044.301   131.636     8,197.286      61      180.796  
## 260.414     4,431.284   537.771    36,538.780    180.796   773.473  
## --------------------------------------------------------------------
zn <- scale(x_mat[,-1])
stargazer(zn, type = "text")
## 
## ==========================================
##    assess bdrms  lotsize colonial llotsize
## ------------------------------------------
## 1  0.350  0.513  -0.284   0.662    -0.340 
## 2  0.375  -0.675  0.087   0.662    0.543  
## 3  -1.029 -0.675 -0.375   -1.495   -0.641 
## 4  -0.881 -0.675 -0.434   0.662    -0.866 
## 5  0.035  0.513  -0.287   0.662    -0.349 
## 6  1.036  1.702  -0.045   0.662    0.277  
## 7  0.546  -0.675 -0.002   0.662    0.367  
## 8  -0.163 -0.675 -0.276   0.662    -0.315 
## 9  -0.836 -0.675 -0.297   -1.495   -0.378 
## 10 -0.624 -0.675 -0.602   -1.495   -1.719 
## 11 -0.018 0.513  -0.297   0.662    -0.378 
## 12 1.057  1.702  -0.194   0.662    -0.082 
## 13 1.241  -0.675  0.316   0.662    0.932  
## 14 -0.382 -0.675 -0.252   -1.495   -0.242 
## 15 -0.296 -0.675 -0.246   0.662    -0.225 
## 16 -0.869 0.513  -0.533   0.662    -1.318 
## 17 -0.125 0.513  -0.304   -1.495   -0.402 
## 18 -0.106 -0.675 -0.186   0.662    -0.063 
## 19 -0.514 -0.675 -0.332   0.662    -0.491 
## 20 0.108  0.513  -0.041   0.662    0.284  
## 21 -0.225 -0.675 -0.347   0.662    -0.540 
## 22 0.032  -0.675 -0.120   0.662    0.104  
## 23 -0.226 -0.675 -0.297   -1.495   -0.377 
## 24 -1.130 0.513  -0.374   -1.495   -0.635 
## 25 -0.798 -0.675  0.040   0.662    0.452  
## 26 -0.227 -0.675 -0.286   -1.495   -0.343 
## 27 -0.507 -0.675 -0.227   -1.495   -0.172 
## 28 0.463  -0.675 -0.044   0.662    0.279  
## 29 1.703  4.079  -0.061   0.662    0.241  
## 30 0.415  0.513   0.074   0.662    0.519  
## 31 -1.028 0.513  -0.414   0.662    -0.786 
## 32 0.727  0.513   0.596   -1.495   1.317  
## 33 -0.959 -0.675 -0.320   0.662    -0.452 
## 34 -0.670 0.513  -0.259   0.662    -0.264 
## 35 0.411  0.513  -0.002   0.662    0.367  
## 36 -1.083 0.513  -0.543   -1.495   -1.369 
## 37 1.434  0.513   0.184   0.662    0.718  
## 38 2.123  1.702   0.650   0.662    1.382  
## 39 -0.276 0.513  -0.258   0.662    -0.259 
## 40 -0.500 -1.864 -0.014   -1.495   0.343  
## 41 -0.391 -0.675 -0.266   0.662    -0.284 
## 42 3.564  1.702   1.888   0.662    2.469  
## 43 -0.445 0.513  -0.194   0.662    -0.081 
## 44 -1.087 -0.675 -0.365   -1.495   -0.604 
## 45 0.401  1.702  -0.234   0.662    -0.192 
## 46 -0.668 -0.675 -0.117   0.662    0.112  
## 47 0.087  -0.675 -0.788   -1.495   -3.671 
## 48 1.676  0.513  -0.089   -1.495   0.176  
## 49 -0.618 -0.675 -0.312   0.662    -0.424 
## 50 -0.383 0.513  -0.232   0.662    -0.186 
## 51 -0.019 -0.675 -0.234   0.662    -0.192 
## 52 -0.377 -1.864  0.614   -1.495   1.339  
## 53 -1.228 -0.675 -0.381   0.662    -0.660 
## 54 -0.989 -0.675 -0.295   0.662    -0.373 
## 55 -0.497 -0.675 -0.060   0.662    0.243  
## 56 -0.351 0.513  -0.334   0.662    -0.497 
## 57 -0.892 0.513  -0.336   0.662    -0.505 
## 58 -0.301 0.513  -0.245   0.662    -0.224 
## 59 -0.179 -0.675 -0.291   0.662    -0.360 
## 60 -0.012 0.513  -0.342   -1.495   -0.525 
## 61 -0.260 -0.675 -0.143   -1.495   0.048  
## 62 -0.308 0.513  -0.348   0.662    -0.543 
## 63 -0.652 2.890  -0.361   0.662    -0.589 
## 64 1.744  1.702   0.670   0.662    1.406  
## 65 0.719  0.513  -0.098   0.662    0.156  
## 66 2.391  0.513   0.290   0.662    0.891  
## 67 0.218  0.513  -0.055   0.662    0.254  
## 68 2.092  0.513   0.598   0.662    1.319  
## 69 1.272  0.513   0.181   -1.495   0.713  
## 70 -0.549 -0.675 -0.267   0.662    -0.288 
## 71 -0.161 -0.675  0.249   -1.495   0.827  
## 72 -0.682 -0.675 -0.297   0.662    -0.378 
## 73 4.122  1.702   2.160   -1.495   2.641  
## 74 -0.414 -0.675 -0.488   0.662    -1.098 
## 75 0.764  -1.864  1.148   -1.495   1.898  
## 76 -0.663 -0.675 -0.344   -1.495   -0.529 
## 77 -0.215 0.513   8.223   0.662    4.654  
## 78 0.459  -0.675 -0.083   0.662    0.191  
## 79 -0.415 0.513  -0.302   0.662    -0.395 
## 80 -0.692 -0.675  0.965   -1.495   1.725  
## 81 -1.189 0.513  -0.462   0.662    -0.984 
## 82 -0.648 -0.675 -0.379   0.662    -0.653 
## 83 -0.094 0.513  -0.111   0.662    0.126  
## 84 0.027  -0.675 -0.291   0.662    -0.361 
## 85 -0.591 -0.675 -0.314   -1.495   -0.431 
## 86 -0.605 -0.675 -0.263   -1.495   -0.276 
## 87 -0.879 -1.864 -0.261   -1.495   -0.270 
## 88 -0.669 0.513  -0.400   0.662    -0.731 
## ------------------------------------------

Calculo de \(|R|\)

Normalizar la matriz X (se muestran las primeras 6 filas)

library(stargazer)
zn<-scale(x_mat[,-1])
stargazer(head(zn,n = 6), type = "text")
## 
## =========================================
##   assess bdrms  lotsize colonial llotsize
## -----------------------------------------
## 1 0.350  0.513  -0.284   0.662    -0.340 
## 2 0.375  -0.675  0.087   0.662    0.543  
## 3 -1.029 -0.675 -0.375   -1.495   -0.641 
## 4 -0.881 -0.675 -0.434   0.662    -0.866 
## 5 0.035  0.513  -0.287   0.662    -0.349 
## 6 1.036  1.702  -0.045   0.662    0.277  
## -----------------------------------------

Calcular la matriz R

library(stargazer)
n<-nrow(zn)
R<-(t(zn)%*%zn)*(1/(n-1))
stargazer(R,type = "text",digits = 4)
## 
## ================================================
##          assess bdrms  lotsize colonial llotsize
## ------------------------------------------------
## assess     1    0.4825 0.3281   0.0829   0.5717 
## bdrms    0.4825   1    0.1363   0.3046   0.1695 
## lotsize  0.3281 0.1363    1     0.0140   0.8079 
## colonial 0.0829 0.3046 0.0140     1      0.0386 
## llotsize 0.5717 0.1695 0.8079   0.0386     1    
## ------------------------------------------------

Calcular \(|R|\)

determinante_R<-det(R)
print(determinante_R)
## [1] 0.1419755

Aplicando la prueba de Farrer Glaubar (Bartlett)

Estadistico \(\chi_{FG}^2\)

m<-ncol(x_mat[,-1])
n<-nrow(x_mat[,-1])
chi_FG<--(n-1-(2*m+5)/6)*log(determinante_R)
print(chi_FG)
## [1] 164.9525

Valor Critico

gl<-m*(m-1)/2
VC<-qchisq(p = 0.95,df = gl)
print(VC)
## [1] 18.30704

Como \(\chi_{FG}^2 \geq V.C.\) se rechaza H0, por lo tanto hay evidencia de colinealidad en los regresores

Uso de la libreria psych

library(psych)
FG_test<-cortest.bartlett(x_mat[,-1])
print(FG_test)
## $chisq
## [1] 164.9525
## 
## $p.value
## [1] 0.000000000000000000000000000003072151
## 
## $df
## [1] 10

Cálculando los VIF para el modelo estimado

Matriz de Correlación de los regresores del modelo (Como se obtuvo con anterioridad)

print(R)
##              assess     bdrms    lotsize   colonial  llotsize
## assess   1.00000000 0.4824739 0.32814633 0.08293582 0.5716654
## bdrms    0.48247394 1.0000000 0.13632563 0.30457549 0.1694902
## lotsize  0.32814633 0.1363256 1.00000000 0.01401865 0.8078552
## colonial 0.08293582 0.3045755 0.01401865 1.00000000 0.0386421
## llotsize 0.57166539 0.1694902 0.80785523 0.03864210 1.0000000

Inversa de la matriz de correlación \(R^-1\)

inversa_R<-solve(R)
print(inversa_R)
##              assess      bdrms    lotsize   colonial   llotsize
## assess    2.1535576 -0.9010888  0.8347216  0.1520968 -1.7586001
## bdrms    -0.9010888  1.5104833 -0.3640744 -0.4021983  0.5687703
## lotsize   0.8347216 -0.3640744  3.2049651  0.1130042 -3.0089889
## colonial  0.1520968 -0.4021983  0.1130042  1.1142184 -0.1531266
## llotsize -1.7586001  0.5687703 -3.0089889 -0.1531266  4.3456744

VIF’s para el modelo estimado

VIFs<-diag(inversa_R)
print(VIFs)
##   assess    bdrms  lotsize colonial llotsize 
## 2.153558 1.510483 3.204965 1.114218 4.345674

Uso de la librería “car” y “mctest”

Obtención de los VIF’s, a través de la librería “car”

library(car)
VIFs_car<-vif(modelo_estimado)
print(VIFs_car)
##   assess    bdrms  lotsize colonial llotsize 
## 2.153558 1.510483 3.204965 1.114218 4.345674

Obtención de los VIF’s, a través de la librería “mctest”

library(mctest)
mc.plot(x = x_mat[,-1],y = hprice1$price,vif = 2,)