Hi!
I am trying yo run a regression using the plm package.
I tried in two different ways, that should give the same result, but
eventually do not; and i cannot understand the reason.
- The first way:
Accellerator.model <- read.delim("~/Desktop/Tesi/Accellerator model.txt")
data <- Accellerator.model
Panel <- plm.data(Accellerator.model,index=c("ID","Year"))
y <- data$Net.Cap.Inv
p <- data$Oil.Price
rev <- data$Revenue
ebi <- data$EBITDA
tas <- data$Tot.Assets
fas <- data$Non.current
tas1 <- data$tas1
rev1 <- data$rev1
rev2 <- data$rev2
fas1 <- data$fas1
cap1 <- data$cap1
# FIXED 1
fixed <- plm(y~fas1+rev+rev1+p,data=pdata,model="within")
summary(fixed)
Oneway (individual) effect Within Model
Call:
plm(formula = y ~ fas1 + rev + rev1 + p, data = pdata, model = "within")
Unbalanced Panel: n=19, T=6-19, N=282
Residuals :
Min. 1st Qu. Median 3rd Qu. Max.
-91.6000 -8.4600 0.0711 7.1000 110.0000
Coefficients :
Estimate Std. Error t-value Pr(>|t|)
fas1 -0.0231717 0.0096980 -2.3893 0.017595 *
rev 0.0922257 0.0035990 25.6251 < 2.2e-16 ***
rev1 0.0127055 0.0058961 2.1549 0.032093 *
p 0.1587968 0.0579552 2.7400 0.006571 **
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Total Sum of Squares: 804760
Residual Sum of Squares: 178290
R-Squared : 0.77845
Adj. R-Squared : 0.71496
F-statistic: 227.513 on 4 and 259 DF, p-value: < 2.22e-16
>
- The second way:
Accellerator.model <- read.delim("~/Desktop/Tesi/Accellerator model.txt")
data <- plm.data(Accellerator.model,index=c("ID","Year"))
data$y <- data$Net.Cap.Inv
data$p <- data$Oil.Price
data$rev <- data$Revenue
data$ebi <- data$EBITDA
data$tas <- data$Tot.Assets
data$fas <- data$Non.current
Panel <- data
fixed <- plm(y~fas1+rev+rev1+p,data=Panel,model="within")
summary(fixed)
Oneway (individual) effect Within Model
Call:
plm(formula = y ~ fas1 + rev + rev1 + p, data = Panel, model = "within")
Unbalanced Panel: n=19, T=9-19, N=296
Residuals :
Min. 1st Qu. Median 3rd Qu. Max.
-75.200 -3.710 -0.604 3.150 80.000
Coefficients :
Estimate Std. Error t-value Pr(>|t|)
fas1 0.0892306 0.0066033 13.5131 < 2.2e-16 ***
rev 0.0120747 0.0111825 1.0798 0.2812
rev1 0.0419186 0.0095914 4.3704 1.764e-05 ***
p 0.0078837 0.0375021 0.2102 0.8337
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Total Sum of Squares: 774610
Residual Sum of Squares: 85942
R-Squared : 0.88905
Adj. R-Squared : 0.81997
F-statistic: 546.893 on 4 and 273 DF, p-value: < 2.22e-16
As you can see, the results are totally different, and I have no
explanation for that!
Thanks for the help
Regards.
Luca.
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