4.2. Correspondence analysis
After performing CA, 5 axes associated to the above-average eigenvalues (equal to 0.153, 0.094, 0.087, 0.073 and 0.064, respectively) have been retained. All together, they keep 51.4% of the total variance (respectively, 16.7; 10.3; 9.5; 7.9; 7.0). The chronology is indicated here by the rank of the speeches in the series (from 1 to 16), not the year.
resCA <- LexCA(TD,ncp=5,graph=FALSE)
resCA$eig
resCA$eig
eigenvalue percentage of variance cumulative percentage of variance
dim 1 0.15304454 16.694431 16.69443
dim 2 0.09444452 10.302213 26.99664
dim 3 0.08725235 9.517676 36.51432
dim 4 0.07259713 7.919053 44.43337
dim 5 0.06430732 7.014782 51.44816
dim 6 0.05417931 5.909996 57.35815
dim 7 0.05310169 5.792447 63.15060
dim 8 0.04900170 5.345212 68.49581
dim 9 0.04787052 5.221821 73.71763
dim 10 0.04690946 5.116986 78.83462
dim 11 0.04428658 4.830876 83.66549
dim 12 0.04323756 4.716447 88.38194
dim 13 0.03849242 4.198837 92.58078
dim 14 0.03701722 4.037919 96.61870
dim 15 0.03099777 3.381304 100.00000mean(resCA$eig[,1])
0.06111601Figure 1 represents the speeches on the first two CA planes, (1,2) and (3,4). In this case, the temporal changes unfold along the first
three axes.
The second axis shows how the first four speeches evolve, while the first axis describes the changes from 4.Gz86 to 12.Sa16, drawing a rough parabola, a usual shape when vocabulary evolves over time.
Finally, axis 3 informs about what is characterizing the last four speeches, which is the opposition between 13.Rj16 and 14. Rj16, at the negative part of this axis, and 15.Sa19 and 16.Sa20, on the positive part. It can be assumed that it is an ideological opposition between the candidates of two opposing parties. They are competing for the head of government by means of motions of censure and election repetitions. As our aim is to present the method and not to analyse these speeches in detail, we do not say more here. Let us just add that both axes 4 and 5 underlines the particularity of the speech 12.Sa16 in relation to those close in time.
plot(resCA, selDoc="ALL", selWord=NULL, axes=c(1,2), graph.type = c("classic"), title="Figure 1. Axes (1,2)")
lines(resCA$row$coord[1:16,1],resCA$row$coord[1:16,2],lwd=2,col="red")
lines(resCA$row$coord[1:16,1],resCA$row$coord[1:16,2],lwd=2,col="red")
plot(resCA, selDoc="ALL", selWord=NULL, axes=c(3,4), graph.type = c("classic"), title="Figure 1. Axes (3,4)")
lines(resCA$row$coord[1:16,3],resCA$row$coord[1:16,4],lwd=2,col="red")
lines(resCA$row$coord[1:16,3],resCA$row$coord[1:16,4],lwd=2,col="red")
summary(resCA, ndoc=10, nword=0, info=FALSE)
Correspondence analysis summaryEigenvalues
Variance % of var. Cumulative % of var.
dim 1 0.153 16.694 16.694
dim 2 0.094 10.302 26.997
dim 3 0.087 9.518 36.514
dim 4 0.073 7.919 44.433
dim 5 0.064 7.015 51.448
Cramer's V 0.247 Inertia 0.917
DOCUMENTS
Coordinates
Only the first 10 elements are shown
Dim 1 Dim 2 Dim 3 Dim 4 Dim 5
1.Su79 0.440 0.414 0.194 0.402 0.173
2.CS81 0.397 0.085 -0.026 0.290 0.147
3.Gz82 0.371 0.147 0.002 0.339 0.310
4.Gz86 0.564 -0.738 0.120 -0.008 -0.144
5.Gz89 0.483 -0.606 0.083 -0.137 0.021
6.Gz93 0.263 0.077 -0.062 -0.104 -0.206
7.Az96 0.266 0.416 -0.130 -0.161 -0.229
8.Az00 0.090 0.272 -0.033 -0.412 -0.279
9.Zp04 0.035 0.210 -0.042 -0.131 -0.244
10.Zp08 -0.113 0.139 0.172 -0.374 -0.209
Contributions (by column total=100)
Only the first 10 elements are shown
Dim 1 Dim 2 Dim 3 Dim 4 Dim 5
1.Su79 9.442 13.545 3.220 16.619 3.468
2.CS81 5.174 0.381 0.038 5.831 1.692
3.Gz82 4.809 1.217 0.000 8.467 7.985
4.Gz86 14.498 40.284 1.148 0.006 2.244
5.Gz89 7.239 18.488 0.374 1.224 0.033
6.Gz93 2.373 0.333 0.229 0.776 3.444
7.Az96 3.166 12.521 1.316 2.441 5.575
8.Az00 0.295 4.329 0.068 12.894 6.672
9.Zp04 0.038 2.257 0.098 1.133 4.473
10.Zp08 0.454 1.102 1.826 10.389 3.668
Square cosinus (by row total=1)
Only the first 10 elements are shown
Dim 1 Dim 2 Dim 3 Dim 4 Dim 5
1.Su79 0.220 0.195 0.043 0.184 0.034
2.CS81 0.157 0.007 0.001 0.084 0.022
3.Gz82 0.138 0.022 0.000 0.115 0.096
4.Gz86 0.274 0.470 0.012 0.000 0.018
5.Gz89 0.172 0.271 0.005 0.014 0.000
6.Gz93 0.081 0.007 0.004 0.013 0.049
7.Az96 0.095 0.232 0.023 0.035 0.070
8.Az00 0.009 0.084 0.001 0.192 0.088
9.Zp04 0.001 0.047 0.002 0.018 0.064
10.Zp08 0.014 0.022 0.033 0.156 0.049
Inertia
1.Su79 0.066
2.CS81 0.050
3.Gz82 0.053
4.Gz86 0.081
5.Gz89 0.064
6.Gz93 0.045
7.Az96 0.051
8.Az00 0.049
9.Zp04 0.045
10.Zp08 0.048