Autocorrelacion, caso Fotocopias

foto <- read.delim("~/Dropbox/Teaching/Econometrics/Foto")
ls(foto)

## [1] "Year"      "copias"    "escolares" "esotrasu"  "esufm"     "otros"    
## [7] "total"

foto$univ = foto$esufm + foto$esotrasu
foto$escyotros = foto$escolares + foto$otros
reg = lm(formula = foto$copias ~ foto$univ + foto$escyotros, data = foto)
summary(reg)

## 
## Call:
## lm(formula = foto$copias ~ foto$univ + foto$escyotros, data = foto)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -16.505  -5.963  -3.339   4.516  20.460 
## 
## Coefficients:
##                Estimate Std. Error t value Pr(>|t|)  
## (Intercept)       5.869      8.258   0.711   0.4851  
## foto$univ         0.923      0.511   1.806   0.0852 .
## foto$escyotros    4.446      2.997   1.483   0.1528  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 9.477 on 21 degrees of freedom
##   (3 observations deleted due to missingness)
## Multiple R-squared:  0.6391, Adjusted R-squared:  0.6047 
## F-statistic: 18.59 on 2 and 21 DF,  p-value: 2.253e-05

## Loading required package: zoo

## 
## Attaching package: 'zoo'

## The following objects are masked from 'package:base':
## 
##     as.Date, as.Date.numeric

## 
##  Durbin-Watson test
## 
## data:  reg
## DW = 0.9214, p-value = 0.001657
## alternative hypothesis: true autocorrelation is greater than 0