Introdução

Exemplo 10-7: Tendência Wooldridge (2006, p.331) - investimento imobiliário e preços de imóveis. Ver também HEISS (p.176), e MOHR (https://www.r-econometrics.com/reproduction/wooldridge/wooldridge10/). São dados anuais de investimento imobiliário real per capita (invpc em milhares de USD) e um índice de preços de imóveis (price, 1982=1) dos EUA de 1947 a 1988.

script MOHR

# https://www.r-econometrics.com/reproduction/wooldridge/wooldridge10/
library(wooldridge)  
data("hseinv")
#esquisse::esquisser()

library(ggplot2)

ggplot(hseinv) +
 aes(x = year, y = lprice) +
 geom_line(size = 1L, colour = "#0c4c8a") +
 theme_minimal()

# Plot de invpc
library(ggplot2)

ggplot(hseinv) +
 aes(x = t, y = invpc) +
 geom_line(size = 1L, colour = "#0c4c8a") +
 theme_minimal()

# Plot de price
ggplot(hseinv) +
 aes(x = t, y = price) +
 geom_line(size = 1L, colour = "#0c4c8a") +
 theme_minimal()

# regressão básica
lm.10.7.1 <- lm(linvpc ~ lprice, data = hseinv)
summary(lm.10.7.1)
## 
## Call:
## lm(formula = linvpc ~ lprice, data = hseinv)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -0.45991 -0.08694 -0.01264  0.08651  0.34672 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -0.55023    0.04303 -12.788 1.03e-15 ***
## lprice       1.24094    0.38242   3.245  0.00238 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.1554 on 40 degrees of freedom
## Multiple R-squared:  0.2084, Adjusted R-squared:  0.1886 
## F-statistic: 10.53 on 1 and 40 DF,  p-value: 0.002376
# regressão incluindo tendencia
lm.10.7.2 <- lm(linvpc ~ lprice + t+lprice_1, data = hseinv)
summary(lm.10.7.2)
## 
## Call:
## lm(formula = linvpc ~ lprice + t + lprice_1, data = hseinv)
## 
## Residuals:
##       Min        1Q    Median        3Q       Max 
## -0.282964 -0.073618 -0.005161  0.081887  0.205221 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -1.086488   0.115368  -9.418 2.29e-11 ***
## lprice       3.259517   0.960045   3.395  0.00165 ** 
## t            0.013447   0.002947   4.562 5.41e-05 ***
## lprice_1    -4.486770   0.958514  -4.681 3.76e-05 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.1153 on 37 degrees of freedom
##   (1 observation deleted due to missingness)
## Multiple R-squared:  0.5641, Adjusted R-squared:  0.5287 
## F-statistic: 15.96 on 3 and 37 DF,  p-value: 8.091e-07

script HEISS

# http://www.urfie.net/downloads10.html
#
library(dynlm);library(stargazer)
data(hseinv, package='wooldridge')

# Define Yearly time series beginning in 1947
tsdata <- ts(hseinv, start=1947)
class(tsdata)
## [1] "mts"    "ts"     "matrix"
# Linear regression of model with lags:
res1 <- dynlm(log(invpc) ~ log(price)                , data=tsdata)
res2 <- dynlm(log(invpc) ~ log(price) + trend(tsdata)+
                      L(log(price)), data=tsdata)
res1$AIC<-AIC(res1)
res2$AIC<-AIC(res2)
star.1 <- stargazer(res1,res2, 
          title="Título: Resultados das Regressões",
          align=TRUE,
          type = "text", style = "all",
          keep.stat=c("aic","rsq", "adj.rsq","n")
          )
## 
## Título: Resultados das Regressões
## ==============================================
##                       Dependent variable:     
##                   ----------------------------
##                            log(invpc)         
##                        (1)            (2)     
## ----------------------------------------------
## log(price)           1.241***      3.260***   
##                      (0.382)        (0.960)   
##                     t = 3.245      t = 3.395  
##                     p = 0.003      p = 0.002  
## trend(tsdata)                      0.013***   
##                                     (0.003)   
##                                    t = 4.562  
##                                   p = 0.0001  
## L(log(price))                      -4.487***  
##                                     (0.959)   
##                                   t = -4.681  
##                                   p = 0.00004 
## Constant            -0.550***      -1.086***  
##                      (0.043)        (0.115)   
##                    t = -12.788    t = -9.418  
##                     p = 0.000      p = 0.000  
## ----------------------------------------------
## Observations            42            41      
## R2                    0.208          0.564    
## Adjusted R2           0.189          0.529    
## Akaike Inf. Crit.    -33.233        -54.983   
## ==============================================
## Note:              *p<0.1; **p<0.05; ***p<0.01