Instalamos la base de datos

library(readr)
library(haven)
library(tidyselect)
library(haven)
Taller_1<-read_dta("C:/Users/Martin Alejandro/OneDrive/Documentos/econometria/eco II/Taller_1.dta")
View(Taller_1)

procedemos a observar los distintos datos

summary(Taller_1)
##      price             sqft           beds          baths            age       
##  Min.   : 50000   Min.   : 704   Min.   :1.00   Min.   :1.000   Min.   : 0.00  
##  1st Qu.: 79900   1st Qu.:1201   1st Qu.:3.00   1st Qu.:2.000   1st Qu.: 8.00  
##  Median : 99950   Median :1516   Median :3.00   Median :2.000   Median :18.00  
##  Mean   :112811   Mean   :1612   Mean   :3.17   Mean   :2.055   Mean   :24.56  
##  3rd Qu.:128000   3rd Qu.:1874   3rd Qu.:4.00   3rd Qu.:2.000   3rd Qu.:38.00  
##  Max.   :500000   Max.   :4300   Max.   :6.00   Max.   :5.000   Max.   :96.00  
##     stories          vacant      
##  Min.   :1.000   Min.   :0.0000  
##  1st Qu.:1.000   1st Qu.:0.0000  
##  Median :1.000   Median :1.0000  
##  Mean   :1.207   Mean   :0.5284  
##  3rd Qu.:1.000   3rd Qu.:1.0000  
##  Max.   :2.000   Max.   :1.0000
library(modeest)
mfv(Taller_1$price) #Moda de la variable
## [1] 75000
mfv(Taller_1$sqft)
## [1] 1064
mfv(Taller_1$beds)
## [1] 3
mfv(Taller_1$baths)
## [1] 2
mfv(Taller_1$age)
## [1] 16
mfv(Taller_1$stories)
## [1] 1
mfv(Taller_1$vacant)
## [1] 1
library(moments) #Se activa el paquete moments para encontrar la curtosis y la asimetria 
## 
## Attaching package: 'moments'
## The following object is masked from 'package:modeest':
## 
##     skewness
skewness(Taller_1$price)  # Coeficiente de asimetria de la variable
## [1] 2.707592
skewness(Taller_1$sqft)
## [1] 1.149429
skewness(Taller_1$beds)
## [1] 0.5459253
skewness(Taller_1$baths)
## [1] 0.351758
skewness(Taller_1$age)
## [1] 1.099061
skewness(Taller_1$stories)
## [1] 1.447726
skewness(Taller_1$vacant)
## [1] -0.1138202
kurtosis(Taller_1)
##     price      sqft      beds     baths       age   stories    vacant 
## 14.772683  4.940148  3.941886  3.624871  3.825866  3.095910  1.012955

Se propone un modelo con las variables que se encuentran en la base de datos

(metros cuadrados, numero de baños, numero de camas, años, numero de pisos, y la dicotomica “vacante”)

price<-Taller_1$price
sqft<-Taller_1$sqft 
beds<-Taller_1$beds
baths<-Taller_1$baths
age<-Taller_1$age
stories<-Taller_1$stories
vacant<-Taller_1$vacant

#variable price sera la variable dependiente, las demas seran las explicativas

modelo1<- lm(price ~ sqft + beds + baths + age + stories + vacant)
res<-residuals(modelo1)
summary(modelo1)
## 
## Call:
## lm(formula = price ~ sqft + beds + baths + age + stories + vacant)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -90740 -17215  -1734  13923 167282 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  36741.177   5529.365   6.645 5.34e-11 ***
## sqft            96.054      2.979  32.248  < 2e-16 ***
## beds        -17786.861   1956.722  -9.090  < 2e-16 ***
## baths        -1009.123   2651.334  -0.381   0.7036    
## age           -331.464     53.565  -6.188 9.36e-10 ***
## stories      -5743.812   3206.128  -1.792   0.0736 .  
## vacant       -9895.778   1938.365  -5.105 4.06e-07 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 28030 on 873 degrees of freedom
## Multiple R-squared:  0.7202, Adjusted R-squared:  0.7183 
## F-statistic: 374.5 on 6 and 873 DF,  p-value: < 2.2e-16

Supuestos

Media Cero

hist(res)

mean(res)
## [1] 2.766841e-12

Exogeneidad

estimated_price <- fitted.values(modelo1)
cor(res, estimated_price)
## [1] 4.084423e-18
plot(modelo1,which = 1)

Normalidad

library(ggplot2)
SampleQuantiles <- rstandard(modelo1)
(ggplot(modelo1,aes(qqnorm(SampleQuantiles)[[1]],SampleQuantiles))
  + geom_point(na.rm = TRUE,col="red")
  + geom_abline()
  + scale_x_continuous(name = "Theorical Quantiles")
  + scale_y_continuous(name = "Sample Quantiles"))

Varianza Constante

(ggplot(modelo1, aes(fitted.values(modelo1),res))
  + geom_point(col=I("red")) 
  + stat_smooth(method = "loess") 
  + stat_binhex(bins = 100) 
  + scale_fill_gradient(low = "blue",high = "black") 
  + geom_hline(yintercept = 0,col ="black", linetype = "dashed")
  + xlab("Fitted Values") 
  + ylab("Residuals"))
## `geom_smooth()` using formula 'y ~ x'

No Autocorrelación

residualesrezagados<-dplyr::lag(res)
plot(res,residualesrezagados)

punto b

predicción

se predice el precio de dos casas las cuales toman valores para la primera: sqft1: 1400 y age1: 20; para la segunda: sqft2: 1800 y age2: 20

Modelo2 <- lm(price ~ sqft + age, data = Taller_1)

library(tibble)
### Primera forma
## Predicción del precio de una casa de 1400 pies cuadrados ##
cvalues1 <- tibble(sqft = 1400,
                   age = 20)
predict(Modelo2, cvalues1, interval = "prediction")
##        fit      lwr      upr
## 1 96710.01 37695.21 155724.8
## Predicción del precio de una casa con 1800 pies cuadrados ##
cvalues2 <- tibble(sqft = 1800,
                   age = 20)
predict(Modelo2, cvalues2, interval = "prediction")
##      fit      lwr      upr
## 1 128675 69663.77 187686.2
### Segunda forma
library(tibble)
library(broom)
tidy(Modelo2, quick=TRUE)
## # A tibble: 3 × 5
##   term        estimate std.error statistic   p.value
##   <chr>          <dbl>     <dbl>     <dbl>     <dbl>
## 1 (Intercept) -11490.    3741.       -3.07 2.20e-  3
## 2 sqft            79.9      1.95     41.0  2.61e-206
## 3 age           -184.      50.2      -3.67 2.62e-  4
nuevo <- data.frame(sqft=c(1400, 1800),
                    age=c(20))

predict(object=Modelo2, newdata=nuevo, interval = "prediction")
##         fit      lwr      upr
## 1  96710.01 37695.21 155724.8
## 2 128674.98 69663.77 187686.2

Punto C

Pruebas Formales

para verificar si el modelo se encuentra con problemas de heteroceasticidad, se realizaran diferentes pruebas, como la de Breush-Pagan, la de White, la de Goldfeld-Quant, entre otras que son las mas reconocidas, con una que indique heteroceasticidad se presume que el modelo presenta problemas.

### Prueba de Breusch-Pagan
library(lmtest)
## Loading required package: zoo
## 
## Attaching package: 'zoo'
## The following objects are masked from 'package:base':
## 
##     as.Date, as.Date.numeric
bptest(modelo1,studentize = FALSE)
## 
##  Breusch-Pagan test
## 
## data:  modelo1
## BP = 785.04, df = 6, p-value < 2.2e-16
bptest(modelo1)
## 
##  studentized Breusch-Pagan test
## 
## data:  modelo1
## BP = 218.16, df = 6, p-value < 2.2e-16
library(car)
## Loading required package: carData
ncvTest(modelo1)
## Non-constant Variance Score Test 
## Variance formula: ~ fitted.values 
## Chisquare = 715.1047, Df = 1, p = < 2.22e-16
### Prueba de White
library(readr)
bptest(modelo1, ~ fitted(modelo1) + I(fitted(modelo1)^2),studentize = FALSE)
## 
##  Breusch-Pagan test
## 
## data:  modelo1
## BP = 1183.4, df = 2, p-value < 2.2e-16
ncvTest(modelo1, ~ fitted(modelo1) + I(fitted(modelo1)^2))
## Non-constant Variance Score Test 
## Variance formula: ~ fitted(modelo1) + I(fitted(modelo1)^2) 
## Chisquare = 1183.431, Df = 2, p = < 2.22e-16
### Prueba de Goldfeld-Quandt
gqtest(modelo1)
## 
##  Goldfeld-Quandt test
## 
## data:  modelo1
## GQ = 1.3854, df1 = 433, df2 = 433, p-value = 0.0003592
## alternative hypothesis: variance increases from segment 1 to 2
gqtest(modelo1,order.by = ~ sqft + beds + baths + age + stories + vacant, data = Taller_1)
## 
##  Goldfeld-Quandt test
## 
## data:  modelo1
## GQ = 0.53517, df1 = 433, df2 = 433, p-value = 1
## alternative hypothesis: variance increases from segment 1 to 2
### Prueba de Park
Residuales2 <- (res^2)

Park1 <- lm(log(Residuales2) ~ log(sqft))
summary(Park1)
## 
## Call:
## lm(formula = log(Residuales2) ~ log(sqft))
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -10.9026  -0.8179   0.4323   1.4269   4.3576 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)   3.4936     1.7024   2.052   0.0405 *  
## log(sqft)     2.1022     0.2319   9.066   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.142 on 878 degrees of freedom
## Multiple R-squared:  0.08561,    Adjusted R-squared:  0.08456 
## F-statistic:  82.2 on 1 and 878 DF,  p-value: < 2.2e-16
Park2 <- lm(log(Residuales2) ~ log(beds))
summary(Park2)
## 
## Call:
## lm(formula = log(Residuales2) ~ log(beds))
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -10.3315  -0.8803   0.4325   1.4715   5.1633 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  18.0892     0.3921  46.132   <2e-16 ***
## log(beds)     0.7304     0.3406   2.145   0.0323 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.234 on 878 degrees of freedom
## Multiple R-squared:  0.005211,   Adjusted R-squared:  0.004078 
## F-statistic: 4.599 on 1 and 878 DF,  p-value: 0.03226
Park3 <- lm(log(Residuales2) ~ log(baths))
summary(Park3)
## 
## Call:
## lm(formula = log(Residuales2) ~ log(baths))
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -10.2372  -0.9064   0.4209   1.4609   4.6879 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  18.1294     0.1572 115.358  < 2e-16 ***
## log(baths)    1.1860     0.2093   5.666 1.98e-08 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.2 on 878 degrees of freedom
## Multiple R-squared:  0.03528,    Adjusted R-squared:  0.03418 
## F-statistic:  32.1 on 1 and 878 DF,  p-value: 1.981e-08
Park4 <- lm(log(Residuales2) ~ log(age + 0.0001))
summary(Park4)
## 
## Call:
## lm(formula = log(Residuales2) ~ log(age + 1e-04))
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -10.1166  -0.9061   0.3690   1.4582   5.0738 
## 
## Coefficients:
##                  Estimate Std. Error t value Pr(>|t|)    
## (Intercept)      19.04980    0.09224 206.521   <2e-16 ***
## log(age + 1e-04) -0.06260    0.02468  -2.536   0.0114 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.232 on 878 degrees of freedom
## Multiple R-squared:  0.007273,   Adjusted R-squared:  0.006143 
## F-statistic: 6.433 on 1 and 878 DF,  p-value: 0.01138
Park5 <- lm(log(Residuales2) ~ log(stories))
summary(Park5)
## 
## Call:
## lm(formula = log(Residuales2) ~ log(stories))
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -10.0417  -0.8627   0.4259   1.4286   4.9716 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  18.75601    0.08397 223.366  < 2e-16 ***
## log(stories)  1.10527    0.26638   4.149 3.66e-05 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.218 on 878 degrees of freedom
## Multiple R-squared:  0.01923,    Adjusted R-squared:  0.01811 
## F-statistic: 17.22 on 1 and 878 DF,  p-value: 3.661e-05
### Prueba de Glesjer

## años 
age.x <- (age + 0.001)
Glesjer <- abs(res)

summary(lm(Glesjer ~ age.x, data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ age.x, data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -21103 -11826  -4634   6304 145909 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 21541.27    1011.52  21.296   <2e-16 ***
## age.x         -56.19      31.53  -1.782   0.0751 .  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19300 on 878 degrees of freedom
## Multiple R-squared:  0.003604,   Adjusted R-squared:  0.002469 
## F-statistic: 3.176 on 1 and 878 DF,  p-value: 0.07508
summary(lm(Glesjer ~ I(1/(age.x)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/(age.x)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -22911 -11974  -4389   6466 147345 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  19934.918    672.253  29.654   <2e-16 ***
## I(1/(age.x))     3.683      2.714   1.357    0.175    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19320 on 878 degrees of freedom
## Multiple R-squared:  0.002093,   Adjusted R-squared:  0.0009565 
## F-statistic: 1.842 on 1 and 878 DF,  p-value: 0.1751
summary(lm(Glesjer ~ I(1/sqrt(age.x)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/sqrt(age.x)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -23077 -12016  -4403   6490 147319 
## 
## Coefficients:
##                  Estimate Std. Error t value Pr(>|t|)    
## (Intercept)      19891.75     678.15  29.332   <2e-16 ***
## I(1/sqrt(age.x))   123.09      86.51   1.423    0.155    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19320 on 878 degrees of freedom
## Multiple R-squared:  0.002301,   Adjusted R-squared:  0.001164 
## F-statistic: 2.025 on 1 and 878 DF,  p-value: 0.1551
summary(lm(Glesjer ~ sqrt(age.x), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ sqrt(age.x), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -22907 -11698  -4411   6293 145001 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  23638.5     1456.0  16.236  < 2e-16 ***
## sqrt(age.x)   -783.9      293.8  -2.668  0.00776 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19260 on 878 degrees of freedom
## Multiple R-squared:  0.008044,   Adjusted R-squared:  0.006914 
## F-statistic:  7.12 on 1 and 878 DF,  p-value: 0.007764
summary(lm(Glesjer ~ I(age.x^2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(age.x^2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -20243 -11930  -4537   6710 146884 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 20399.2177   778.1990   26.21   <2e-16 ***
## I(age.x^2)     -0.2313     0.4131   -0.56    0.576    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19340 on 878 degrees of freedom
## Multiple R-squared:  0.0003568,  Adjusted R-squared:  -0.0007818 
## F-statistic: 0.3134 on 1 and 878 DF,  p-value: 0.5758
summary(lm(Glesjer ~ I(age.x^-2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(age.x^-2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -22906 -11974  -4389   6465 147346 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 1.994e+04  6.722e+02  29.658   <2e-16 ***
## I(age.x^-2) 3.678e-03  2.714e-03   1.355    0.176    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19320 on 878 degrees of freedom
## Multiple R-squared:  0.002088,   Adjusted R-squared:  0.0009512 
## F-statistic: 1.837 on 1 and 878 DF,  p-value: 0.1757
## pies cuadrados 
summary(lm(Glesjer ~ sqft, data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ sqft, data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -45149  -9764  -2894   7419 113946 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -8775.521   1809.443   -4.85 1.46e-06 ***
## sqft           17.951      1.066   16.84  < 2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 16810 on 878 degrees of freedom
## Multiple R-squared:  0.2441, Adjusted R-squared:  0.2433 
## F-statistic: 283.6 on 1 and 878 DF,  p-value: < 2.2e-16
summary(lm(Glesjer ~ I(1/(sqft)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/(sqft)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -31771 -11071  -3165   7534 133372 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)     43984       2083   21.11   <2e-16 ***
## I(1/(sqft)) -34858880    2916934  -11.95   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 17940 on 878 degrees of freedom
## Multiple R-squared:  0.1399, Adjusted R-squared:  0.1389 
## F-statistic: 142.8 on 1 and 878 DF,  p-value: < 2.2e-16
summary(lm(Glesjer ~ I(1/sqrt(sqft)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/sqrt(sqft)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -34678 -10887  -3177   7479 129623 
## 
## Coefficients:
##                 Estimate Std. Error t value Pr(>|t|)    
## (Intercept)        71308       3937   18.11   <2e-16 ***
## I(1/sqrt(sqft)) -1979307     150612  -13.14   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 17680 on 878 degrees of freedom
## Multiple R-squared:  0.1644, Adjusted R-squared:  0.1634 
## F-statistic: 172.7 on 1 and 878 DF,  p-value: < 2.2e-16
summary(lm(Glesjer ~ sqrt(sqft), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ sqrt(sqft), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -41540 -10045  -2931   7420 119810 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -36310.28    3659.48  -9.922   <2e-16 ***
## sqrt(sqft)    1424.33      91.15  15.627   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 17110 on 878 degrees of freedom
## Multiple R-squared:  0.2176, Adjusted R-squared:  0.2167 
## F-statistic: 244.2 on 1 and 878 DF,  p-value: < 2.2e-16
summary(lm(Glesjer ~ I(sqft^2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(sqft^2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -51157  -9414  -2729   6950 112852 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 5.867e+03  9.368e+02   6.262 5.94e-10 ***
## I(sqft^2)   4.961e-03  2.632e-04  18.849  < 2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 16320 on 878 degrees of freedom
## Multiple R-squared:  0.2881, Adjusted R-squared:  0.2873 
## F-statistic: 355.3 on 1 and 878 DF,  p-value: < 2.2e-16
summary(lm(Glesjer ~ I(sqft^-2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(sqft^-2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -27248 -11271  -3590   6806 138788 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  3.013e+04  1.194e+03  25.235   <2e-16 ***
## I(sqft^-2)  -1.954e+10  2.001e+09  -9.762   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18370 on 878 degrees of freedom
## Multiple R-squared:  0.09792,    Adjusted R-squared:  0.09689 
## F-statistic:  95.3 on 1 and 878 DF,  p-value: < 2.2e-16
## camas 
summary(lm(Glesjer ~ beds, data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ beds, data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -26743 -11745  -4043   6701 147861 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)   6386.2     3023.3   2.112   0.0349 *  
## beds          4344.8      931.7   4.663  3.6e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19100 on 878 degrees of freedom
## Multiple R-squared:  0.02417,    Adjusted R-squared:  0.02306 
## F-statistic: 21.75 on 1 and 878 DF,  p-value: 3.595e-06
summary(lm(Glesjer ~ I(1/(beds)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/(beds)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -22399 -11996  -4070   6806 147176 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)    29258       2820  10.374  < 2e-16 ***
## I(1/(beds))   -27459       8285  -3.314 0.000957 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19220 on 878 degrees of freedom
## Multiple R-squared:  0.01236,    Adjusted R-squared:  0.01123 
## F-statistic: 10.98 on 1 and 878 DF,  p-value: 0.0009569
summary(lm(Glesjer ~ I(1/sqrt(beds)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/sqrt(beds)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -23429 -11974  -4024   6935 147322 
## 
## Coefficients:
##                 Estimate Std. Error t value Pr(>|t|)    
## (Intercept)        41418       5740   7.216 1.16e-12 ***
## I(1/sqrt(beds))   -37168       9973  -3.727 0.000206 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19190 on 878 degrees of freedom
## Multiple R-squared:  0.01557,    Adjusted R-squared:  0.01445 
## F-statistic: 13.89 on 1 and 878 DF,  p-value: 0.0002063
summary(lm(Glesjer ~ sqrt(beds), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ sqrt(beds), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -25655 -11837  -4003   6865 147680 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)    -5900       5941  -0.993    0.321    
## sqrt(beds)     14723       3337   4.413 1.15e-05 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19130 on 878 degrees of freedom
## Multiple R-squared:  0.0217, Adjusted R-squared:  0.02058 
## F-statistic: 19.47 on 1 and 878 DF,  p-value: 1.148e-05
summary(lm(Glesjer ~ I(beds^2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(beds^2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -28573 -11586  -4045   6723 148154 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  13045.7     1575.3   8.282 4.51e-16 ***
## I(beds^2)      675.8      136.6   4.948 8.99e-07 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19070 on 878 degrees of freedom
## Multiple R-squared:  0.02713,    Adjusted R-squared:  0.02602 
## F-statistic: 24.48 on 1 and 878 DF,  p-value: 8.986e-07
summary(lm(Glesjer ~ I(beds^-2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(beds^-2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -21409 -12081  -4348   6764 147002 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)    23044       1362  16.913   <2e-16 ***
## I(beds^-2)    -24877      10336  -2.407   0.0163 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19280 on 878 degrees of freedom
## Multiple R-squared:  0.006555,   Adjusted R-squared:  0.005423 
## F-statistic: 5.793 on 1 and 878 DF,  p-value: 0.01629
## Baños 
summary(lm(Glesjer ~ baths, data = Taller_1)) 
## 
## Call:
## lm(formula = Glesjer ~ baths, data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -28588 -11022  -3326   7253 138403 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)   1217.7     2001.7   0.608    0.543    
## baths         9220.3      926.7   9.950   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18330 on 878 degrees of freedom
## Multiple R-squared:  0.1013, Adjusted R-squared:  0.1003 
## F-statistic:    99 on 1 and 878 DF,  p-value: < 2.2e-16
summary(lm(Glesjer ~ I(1/(baths)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/(baths)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -23931 -11726  -3814   6972 143061 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)     30416       1719  17.694  < 2e-16 ***
## I(1/(baths))   -18585       2894  -6.423 2.19e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18900 on 878 degrees of freedom
## Multiple R-squared:  0.04488,    Adjusted R-squared:  0.04379 
## F-statistic: 41.25 on 1 and 878 DF,  p-value: 2.188e-10
summary(lm(Glesjer ~ I(1/sqrt(baths)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/sqrt(baths)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -24966 -11613  -3847   6973 142025 
## 
## Coefficients:
##                  Estimate Std. Error t value Pr(>|t|)    
## (Intercept)         44523       3427  12.992  < 2e-16 ***
## I(1/sqrt(baths))   -33371       4613  -7.234 1.02e-12 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18790 on 878 degrees of freedom
## Multiple R-squared:  0.05624,    Adjusted R-squared:  0.05517 
## F-statistic: 52.32 on 1 and 878 DF,  p-value: 1.025e-12
summary(lm(Glesjer ~ sqrt(baths), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ sqrt(baths), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -27438 -11377  -3337   7016 139553 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)   -13417       3756  -3.572 0.000374 ***
## sqrt(baths)    23756       2620   9.065  < 2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18490 on 878 degrees of freedom
## Multiple R-squared:  0.08559,    Adjusted R-squared:  0.08455 
## F-statistic: 82.18 on 1 and 878 DF,  p-value: < 2.2e-16
summary(lm(Glesjer ~ I(baths^2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(baths^2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -31666 -10720  -3152   6977 137112 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)   9387.2     1131.4   8.297    4e-16 ***
## I(baths^2)    2309.1      204.3  11.300   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18070 on 878 degrees of freedom
## Multiple R-squared:  0.127,  Adjusted R-squared:  0.126 
## F-statistic: 127.7 on 1 and 878 DF,  p-value: < 2.2e-16
summary(lm(Glesjer ~ I(baths^-2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(baths^-2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -22490 -11933  -3971   6653 144501 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  23983.2      978.7  24.504  < 2e-16 ***
## I(baths^-2) -10828.8     2092.6  -5.175 2.83e-07 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 19050 on 878 degrees of freedom
## Multiple R-squared:  0.0296, Adjusted R-squared:  0.02849 
## F-statistic: 26.78 on 1 and 878 DF,  p-value: 2.83e-07
## pisos o plantas 
summary(lm(Glesjer ~ stories, data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ stories, data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -27950 -11526  -3667   6219 139042 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)     7870       2002   3.931 9.11e-05 ***
## stories        10185       1572   6.477 1.55e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18890 on 878 degrees of freedom
## Multiple R-squared:  0.0456, Adjusted R-squared:  0.04452 
## F-statistic: 41.95 on 1 and 878 DF,  p-value: 1.554e-10
summary(lm(Glesjer ~ I(1/(stories)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/(stories)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -27950 -11526  -3667   6219 139042 
## 
## Coefficients:
##                Estimate Std. Error t value Pr(>|t|)    
## (Intercept)       38425       2891  13.292  < 2e-16 ***
## I(1/(stories))   -20370       3145  -6.477 1.55e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18890 on 878 degrees of freedom
## Multiple R-squared:  0.0456, Adjusted R-squared:  0.04452 
## F-statistic: 41.95 on 1 and 878 DF,  p-value: 1.554e-10
summary(lm(Glesjer ~ I(1/sqrt(stories)), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(1/sqrt(stories)), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -27950 -11526  -3667   6219 139042 
## 
## Coefficients:
##                    Estimate Std. Error t value Pr(>|t|)    
## (Intercept)           52829       5084  10.392  < 2e-16 ***
## I(1/sqrt(stories))   -34774       5369  -6.477 1.55e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18890 on 878 degrees of freedom
## Multiple R-squared:  0.0456, Adjusted R-squared:  0.04452 
## F-statistic: 41.95 on 1 and 878 DF,  p-value: 1.554e-10
summary(lm(Glesjer ~ sqrt(stories), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ sqrt(stories), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -27950 -11526  -3667   6219 139042 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)      -6534       4170  -1.567    0.118    
## sqrt(stories)    24589       3796   6.477 1.55e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18890 on 878 degrees of freedom
## Multiple R-squared:  0.0456, Adjusted R-squared:  0.04452 
## F-statistic: 41.95 on 1 and 878 DF,  p-value: 1.554e-10
summary(lm(Glesjer ~ I(stories^2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(stories^2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -27950 -11526  -3667   6219 139042 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept)   14659.7     1061.6  13.809  < 2e-16 ***
## I(stories^2)   3395.0      524.2   6.477 1.55e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18890 on 878 degrees of freedom
## Multiple R-squared:  0.0456, Adjusted R-squared:  0.04452 
## F-statistic: 41.95 on 1 and 878 DF,  p-value: 1.554e-10
summary(lm(Glesjer ~ I(stories^-2), data = Taller_1))
## 
## Call:
## lm(formula = Glesjer ~ I(stories^-2), data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -27950 -11526  -3667   6219 139042 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)      31635       1882  16.806  < 2e-16 ***
## I(stories^-2)   -13580       2097  -6.477 1.55e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 18890 on 878 degrees of freedom
## Multiple R-squared:  0.0456, Adjusted R-squared:  0.04452 
## F-statistic: 41.95 on 1 and 878 DF,  p-value: 1.554e-10

punto d

se procede a estimar los a1 y a2 que suponen una estructura de la heteroceasticidad aditiva y/o multiplicativa

Modelo1 <- lm(price ~ sqft + beds + baths + age + stories + vacant, data = Taller_1)
summary(Modelo1)
## 
## Call:
## lm(formula = price ~ sqft + beds + baths + age + stories + vacant, 
##     data = Taller_1)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -90740 -17215  -1734  13923 167282 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  36741.177   5529.365   6.645 5.34e-11 ***
## sqft            96.054      2.979  32.248  < 2e-16 ***
## beds        -17786.861   1956.722  -9.090  < 2e-16 ***
## baths        -1009.123   2651.334  -0.381   0.7036    
## age           -331.464     53.565  -6.188 9.36e-10 ***
## stories      -5743.812   3206.128  -1.792   0.0736 .  
## vacant       -9895.778   1938.365  -5.105 4.06e-07 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 28030 on 873 degrees of freedom
## Multiple R-squared:  0.7202, Adjusted R-squared:  0.7183 
## F-statistic: 374.5 on 6 and 873 DF,  p-value: < 2.2e-16
Residuales1 <- residuals(Modelo1)
Resid2 <- Residuales1^2

# Con exponencial
logud1 <- log(Resid2)
var1 <- lm(logud1 ~ sqft + beds + baths + age + stories + vacant, data = Taller_1)
summary(var1)
## 
## Call:
## lm(formula = logud1 ~ sqft + beds + baths + age + stories + vacant, 
##     data = Taller_1)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -10.7235  -0.7729   0.3912   1.3590   4.3669 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 18.2422397  0.4138533  44.079  < 2e-16 ***
## sqft         0.0017948  0.0002229   8.051 2.68e-15 ***
## beds        -0.7210164  0.1464537  -4.923 1.02e-06 ***
## baths        0.1671947  0.1984429   0.843    0.400    
## age         -0.0011555  0.0040092  -0.288    0.773    
## stories     -0.1151625  0.2399672  -0.480    0.631    
## vacant      -0.2104465  0.1450797  -1.451    0.147    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.098 on 873 degrees of freedom
## Multiple R-squared:  0.1277, Adjusted R-squared:  0.1217 
## F-statistic: 21.29 on 6 and 873 DF,  p-value: < 2.2e-16
w <- 1/exp(fitted(var1))

MCGF1 <-lm(price ~ sqft + beds + baths + age + stories + vacant, weights = w)
summary(MCGF1)
## 
## Call:
## lm(formula = price ~ sqft + beds + baths + age + stories + vacant, 
##     weights = w)
## 
## Weighted Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.2104 -1.0376 -0.2312  0.9359  7.4328 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 31574.489   4023.337   7.848 1.24e-14 ***
## sqft           69.642      2.705  25.745  < 2e-16 ***
## beds        -6791.853   1407.623  -4.825 1.65e-06 ***
## baths       -3622.475   1839.187  -1.970   0.0492 *  
## age          -208.733     37.156  -5.618 2.60e-08 ***
## stories      2963.214   2602.607   1.139   0.2552    
## vacant      -6300.409   1321.778  -4.767 2.19e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 1.649 on 873 degrees of freedom
## Multiple R-squared:  0.6406, Adjusted R-squared:  0.6381 
## F-statistic: 259.3 on 6 and 873 DF,  p-value: < 2.2e-16
# Sin exponencial
w <- (fitted(var1))
MCGF2 <-lm(price ~ sqft + beds + baths + age + stories + vacant, weights = w)
summary(MCGF2)
## 
## Call:
## lm(formula = price ~ sqft + beds + baths + age + stories + vacant, 
##     weights = w)
## 
## Weighted Residuals:
##     Min      1Q  Median      3Q     Max 
## -427645  -76170   -6604   63157  774179 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  37113.182   5655.100   6.563 9.05e-11 ***
## sqft            98.234      2.985  32.905  < 2e-16 ***
## beds        -18702.390   1996.782  -9.366  < 2e-16 ***
## baths         -952.480   2706.901  -0.352   0.7250    
## age           -346.535     54.841  -6.319 4.19e-10 ***
## stories      -6251.973   3252.402  -1.922   0.0549 .  
## vacant      -10187.413   1989.117  -5.122 3.73e-07 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 125200 on 873 degrees of freedom
## Multiple R-squared:  0.7272, Adjusted R-squared:  0.7254 
## F-statistic: 387.9 on 6 and 873 DF,  p-value: < 2.2e-16

punto e

encontrar estimaciones de MCG

### punto e
M1 <- log(resid(modelo1)^2)
varreg1 <- lm(M1 ~ sqft + beds + baths + age + stories + vacant, data = Taller_1)
summary(varreg1)
## 
## Call:
## lm(formula = M1 ~ sqft + beds + baths + age + stories + vacant, 
##     data = Taller_1)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -10.7235  -0.7729   0.3912   1.3590   4.3669 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 18.2422397  0.4138533  44.079  < 2e-16 ***
## sqft         0.0017948  0.0002229   8.051 2.68e-15 ***
## beds        -0.7210164  0.1464537  -4.923 1.02e-06 ***
## baths        0.1671947  0.1984429   0.843    0.400    
## age         -0.0011555  0.0040092  -0.288    0.773    
## stories     -0.1151625  0.2399672  -0.480    0.631    
## vacant      -0.2104465  0.1450797  -1.451    0.147    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.098 on 873 degrees of freedom
## Multiple R-squared:  0.1277, Adjusted R-squared:  0.1217 
## F-statistic: 21.29 on 6 and 873 DF,  p-value: < 2.2e-16
p <- 1/exp(fitted(varreg1))
MCGF <-lm(price ~ sqft + beds + baths + age + stories + vacant, weights = p)
summary(MCGF)
## 
## Call:
## lm(formula = price ~ sqft + beds + baths + age + stories + vacant, 
##     weights = p)
## 
## Weighted Residuals:
##     Min      1Q  Median      3Q     Max 
## -5.2104 -1.0376 -0.2312  0.9359  7.4328 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 31574.489   4023.337   7.848 1.24e-14 ***
## sqft           69.642      2.705  25.745  < 2e-16 ***
## beds        -6791.853   1407.623  -4.825 1.65e-06 ***
## baths       -3622.475   1839.187  -1.970   0.0492 *  
## age          -208.733     37.156  -5.618 2.60e-08 ***
## stories      2963.214   2602.607   1.139   0.2552    
## vacant      -6300.409   1321.778  -4.767 2.19e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 1.649 on 873 degrees of freedom
## Multiple R-squared:  0.6406, Adjusted R-squared:  0.6381 
## F-statistic: 259.3 on 6 and 873 DF,  p-value: < 2.2e-16
ResiMCGF <- residuals(MCGF)

### Prueba de Breusch-Pagan
library(lmtest)
bptest(MCGF,studentize = FALSE)
## 
##  Breusch-Pagan test
## 
## data:  MCGF
## BP = 1.2107e+11, df = 6, p-value < 2.2e-16
bptest(MCGF)
## 
##  studentized Breusch-Pagan test
## 
## data:  MCGF
## BP = 1.3162e-07, df = 6, p-value = 1
### Errores estandar robustos ###
library(sandwich)
coeftest(Modelo1, vcov. = vcovHC, type = "HC4")
## 
## t test of coefficients:
## 
##                Estimate  Std. Error t value  Pr(>|t|)    
## (Intercept)  36741.1769   6785.9475  5.4143 7.956e-08 ***
## sqft            96.0541      6.7059 14.3237 < 2.2e-16 ***
## beds        -17786.8611   2977.7770 -5.9732 3.384e-09 ***
## baths        -1009.1226   3564.9137 -0.2831    0.7772    
## age           -331.4641     65.4809 -5.0620 5.061e-07 ***
## stories      -5743.8121   4660.1475 -1.2325    0.2181    
## vacant       -9895.7775   2070.3602 -4.7797 2.059e-06 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
summary(modelo1)
## 
## Call:
## lm(formula = price ~ sqft + beds + baths + age + stories + vacant)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -90740 -17215  -1734  13923 167282 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  36741.177   5529.365   6.645 5.34e-11 ***
## sqft            96.054      2.979  32.248  < 2e-16 ***
## beds        -17786.861   1956.722  -9.090  < 2e-16 ***
## baths        -1009.123   2651.334  -0.381   0.7036    
## age           -331.464     53.565  -6.188 9.36e-10 ***
## stories      -5743.812   3206.128  -1.792   0.0736 .  
## vacant       -9895.778   1938.365  -5.105 4.06e-07 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 28030 on 873 degrees of freedom
## Multiple R-squared:  0.7202, Adjusted R-squared:  0.7183 
## F-statistic: 374.5 on 6 and 873 DF,  p-value: < 2.2e-16

punto f

predecir nuevamente con valores la primera: sqft1: 1400 y age1: 20; para la segunda: sqft2: 1800 y age2: 20

precio.fact = 31574.489+ 69.642*sqft + -208.733*age

ModeloFP<- lm(precio.fact ~ sqft + age, data =Taller_1)
summary(ModeloFP)
## Warning in summary.lm(ModeloFP): essentially perfect fit: summary may be
## unreliable
## 
## Call:
## lm(formula = precio.fact ~ sqft + age, data = Taller_1)
## 
## Residuals:
##        Min         1Q     Median         3Q        Max 
## -9.146e-11 -8.280e-12 -1.610e-12  5.750e-12  9.245e-10 
## 
## Coefficients:
##               Estimate Std. Error    t value Pr(>|t|)    
## (Intercept)  3.157e+04  5.494e-12  5.747e+15   <2e-16 ***
## sqft         6.964e+01  2.859e-15  2.435e+16   <2e-16 ***
## age         -2.087e+02  7.367e-14 -2.833e+15   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 4.412e-11 on 877 degrees of freedom
## Multiple R-squared:      1,  Adjusted R-squared:      1 
## F-statistic: 3.29e+32 on 2 and 877 DF,  p-value: < 2.2e-16
tidy(ModeloFP, quick=TRUE)
## Warning in summary.lm(x): essentially perfect fit: summary may be unreliable
## # A tibble: 3 × 5
##   term        estimate std.error statistic p.value
##   <chr>          <dbl>     <dbl>     <dbl>   <dbl>
## 1 (Intercept)  31574.   5.49e-12   5.75e15       0
## 2 sqft            69.6  2.86e-15   2.44e16       0
## 3 age           -209.   7.37e-14  -2.83e15       0
nuevoFP <- data.frame(sqft=c(1400, 1800),
                    age=c(20))

predict(object=ModeloFP, newdata=nuevoFP, interval = "prediction")
##        fit      lwr      upr
## 1 124898.6 124898.6 124898.6
## 2 152755.4 152755.4 152755.4