>  mdata <-read.table("panel.csv", header=T, sep=",")
> id <-mdata[,1]
> year<-mdata[,2]
> y <-mdata[,3]
> x <-mdata[,4]
> ols_result <-lm(y~x)
> summary(ols_result)

Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-2.52559 -0.39145  0.07648  0.51871  1.61471 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)    
(Intercept)  1.43810    0.10262   14.01   <2e-16 ***
x            0.84544    0.03498   24.17   <2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.799 on 313 degrees of freedom
Multiple R-squared:  0.6511,    Adjusted R-squared:   0.65 
F-statistic: 584.1 on 1 and 313 DF,  p-value: < 2.2e-16

> mydata <-data.frame(id,year,y,x)
> library(lattice)
> xyplot(y[1:28]~year[1:28]|as.character(id[1:28]), data=mydata, xlab="year", ylab="y", type="l", as.table=TRUE)
> xyplot(y[1:28]~year[1:28], groups=as.character(id[1:28]), data=mydata, xlab="year", ylab="y", type="l", as.table=TRUE, auto.key = list(x = 0.1, y = 0.8, corner = c(0, 0)))

> library(plm)
> fixed <-plm(y~x, data=mydata, index=c("id","year"), model="within")
> summary(fixed)
Oneway (individual) effect Within Model

Call:
plm(formula = y ~ x, data = mydata, model = "within", index = c("id", 
    "year"))

Balanced Panel: n = 45, T = 7, N = 315

Residuals:
      Min.    1st Qu.     Median    3rd Qu.       Max. 
-1.2919733 -0.1525946  0.0088823  0.2231488  1.0914112 

Coefficients:
  Estimate Std. Error t-value Pr(>|t|)  
x 0.195584   0.081855  2.3894  0.01757 *
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Total Sum of Squares:    36.917
Residual Sum of Squares: 36.15
R-Squared:      0.020783
Adj. R-Squared: -0.14303
F-statistic: 5.70919 on 1 and 269 DF, p-value: 0.017565

> pFtest(fixed,pool)

        F test for individual effects

data:  y ~ x
F = 27.683, df1 = 44, df2 = 269, p-value < 2.2e-16
alternative hypothesis: significant effects

# fixed effects: alpha+u_i
> summary(fixef(fixed))  
   Estimate Std. Error t-value  Pr(>|t|)    
1   3.28080    0.15422 21.2742 < 2.2e-16 ***
2   3.11843    0.29516 10.5653 < 2.2e-16 ***
3   3.02394    0.25892 11.6790 < 2.2e-16 ***
4   2.80321    0.20902 13.4113 < 2.2e-16 ***
5   4.26975    0.33127 12.8891 < 2.2e-16 ***
6   1.75536    0.26685  6.5780 2.475e-10 ***
7   2.72358    0.15102 18.0342 < 2.2e-16 ***
8   4.49926    0.35651 12.6202 < 2.2e-16 ***
9   3.76266    0.26940 13.9666 < 2.2e-16 ***
10  5.37197    0.40826 13.1582 < 2.2e-16 ***
11  2.74967    0.26812 10.2553 < 2.2e-16 ***
12  2.51395    0.21171 11.8744 < 2.2e-16 ***
13  3.20393    0.19897 16.1023 < 2.2e-16 ***
14  3.20121    0.25105 12.7513 < 2.2e-16 ***
15  2.85323    0.21248 13.4281 < 2.2e-16 ***
16  3.59978    0.28924 12.4457 < 2.2e-16 ***
17  3.12772    0.35804  8.7356 2.639e-16 ***
18  3.79249    0.32649 11.6161 < 2.2e-16 ***
19  3.92342    0.30444 12.8874 < 2.2e-16 ***
20  2.64026    0.26174 10.0872 < 2.2e-16 ***
21  1.84157    0.23136  7.9596 4.853e-14 ***
22  0.68081    0.20937  3.2517  0.001293 ** 
23  4.29891    0.38487 11.1698 < 2.2e-16 ***
24  3.29837    0.24475 13.4766 < 2.2e-16 ***
25  3.55406    0.31790 11.1797 < 2.2e-16 ***
26  3.86666    0.22426 17.2416 < 2.2e-16 ***
27  3.88323    0.30878 12.5761 < 2.2e-16 ***
28  0.65306    0.14345  4.5524 8.042e-06 ***
29  2.94679    0.23379 12.6046 < 2.2e-16 ***
30  1.28630    0.17853  7.2052 5.843e-12 ***
31  5.10160    0.39886 12.7905 < 2.2e-16 ***
32  1.23127    0.14624  8.4197 2.278e-15 ***
33  2.40025    0.14390 16.6800 < 2.2e-16 ***
34  4.96925    0.42253 11.7608 < 2.2e-16 ***
35  0.92362    0.14194  6.5070 3.729e-10 ***
36  2.61346    0.19394 13.4754 < 2.2e-16 ***
37  4.51959    0.41697 10.8390 < 2.2e-16 ***
38  4.32519    0.31243 13.8437 < 2.2e-16 ***
39  2.36210    0.28097  8.4069 2.484e-15 ***
40  3.27609    0.28583 11.4618 < 2.2e-16 ***
41  2.90388    0.24818 11.7007 < 2.2e-16 ***
42  4.08466    0.28724 14.2204 < 2.2e-16 ***
43  3.58245    0.22082 16.2232 < 2.2e-16 ***
44  3.70293    0.30053 12.3213 < 2.2e-16 ***
45  3.28288    0.30251 10.8520 < 2.2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
 


> random <-plm(y~x, data=mydata, index=c("id","year"), model="random")
> summary(random)
Oneway (individual) effect Random Effect Model 
   (Swamy-Arora's transformation)

Call:
plm(formula = y ~ x, data = mydata, model = "random", index = c("id", 
    "year"))

Balanced Panel: n = 45, T = 7, N = 315

Effects:
                 var std.dev share
idiosyncratic 0.1344  0.3666 0.213
individual    0.4954  0.7038 0.787
theta: 0.8068

Residuals:
     Min.   1st Qu.    Median   3rd Qu.      Max. 
-1.358754 -0.206733  0.053443  0.251733  0.815222 

Coefficients:
            Estimate Std. Error t-value  Pr(>|t|)    
(Intercept)  2.29119    0.19784 11.5810 < 2.2e-16 ***
x            0.52182    0.06180  8.4438 1.164e-15 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Total Sum of Squares:    56.909
Residual Sum of Squares: 46.351
R-Squared:      0.18553
Adj. R-Squared: 0.18292
F-statistic: 71.2972 on 1 and 313 DF, p-value: 1.1642e-15

> phtest(random, fixed)

        Hausman Test

data:  y ~ x
chisq = 36.942, df = 1, p-value = 1.217e-09
alternative hypothesis: one model is inconsistent
 
> pool <-plm(y~x, data=mydata, index=c("id","year"), model="pooling")
> summary(pool)
Pooling Model

Call:
plm(formula = y ~ x, data = mydata, model = "pooling", 
    index = c("id", "year"))

Balanced Panel: n = 45, T = 7, N = 315

Residuals:
     Min.   1st Qu.    Median   3rd Qu.      Max. 
-2.525593 -0.391450  0.076475  0.518710  1.614709 

Coefficients:
            Estimate Std. Error t-value  Pr(>|t|)    
(Intercept) 1.438101   0.102621  14.014 < 2.2e-16 ***
x           0.845438   0.034983  24.167 < 2.2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Total Sum of Squares:    572.75
Residual Sum of Squares: 199.84
R-Squared:      0.65108
Adj. R-Squared: 0.64997
F-statistic: 584.061 on 1 and 313 DF, p-value: < 2.22e-16
> plmtest(pool, type=c("bp"))

        Lagrange Multiplier Test - (Breusch-Pagan) for balanced panels

data:  y ~ x
chisq = 516.79, df = 1, p-value < 2.2e-16
alternative hypothesis: significant effects