Interpretting PC Scores

car

#1

Hello,
I’ve done the following so far:
’> #install.packages(“car”)

library(car)
X <- Pottery[,-1]
S = cov(X)
round(S, 2)
Al Fe Mg Ca Na
Al 8.96 -5.69 -5.21 -0.23 -0.19
Fe -5.69 5.81 4.73 0.19 0.22
Mg -5.21 4.73 4.75 0.19 0.19
Ca -0.23 0.19 0.19 0.01 0.01
Na -0.19 0.22 0.19 0.01 0.02
E = eigen(S)$vector
rownames(E) = colnames(X)
colnames(E) <- paste(“PC”, 1:ncol(X))
round(E, 2)
PC 1 PC 2 PC 3 PC 4 PC 5
Al 0.68 0.73 -0.04 -0.01 -0.01
Fe -0.54 0.54 0.64 -0.03 0.00
Mg -0.49 0.42 -0.77 -0.02 0.03
Ca -0.02 0.01 -0.03 -0.08 -1.00
Na -0.02 0.03 0.00 1.00 -0.08
eigen(S)$value -> L
round(L, 2)
[1] 17.24 1.77 0.52 0.01 0.00
scores = as.matrix(X) %*% E
scores.data <- data.frame(round(scores[,1:2], 2))
scores.data[,3] <- as.numeric(Pottery[,1]) # the site information
colnames(scores.data) <- c(“PC scores 1”, “PC scores 2”, “Site”)
scores.data
PC scores 1 PC scores 2 Site
1 3.90 16.11 4
2 3.88 15.34 4
3 4.20 16.12 4
4 1.61 14.20 4
5 2.95 16.13 4
6 2.32 12.80 4
7 2.48 11.46 4
8 1.87 14.06 4
9 2.36 12.97 4
10 1.82 16.54 4
11 2.32 14.76 4
12 2.61 15.46 4
13 2.84 14.75 4
14 3.08 14.26 4
15 3.15 13.20 2
16 3.13 12.96 2
17 11.45 14.34 3
18 9.16 13.10 3
19 11.12 14.24 3
20 10.91 14.45 3
21 13.00 16.31 3
22 11.18 13.77 1
23 11.52 14.27 1
24 10.62 12.92 1
25 8.27 12.57 1
26 11.83 15.09 1’

And i’m struggling to interpret the PC loadings above, I was wondering if you could help me in interpret the PC loadings I have?
Kind regards
Jennifer


#2

What do you mean by “interpret PC loadings”?

Are you looking to process this data and generate some kind of output. Show us what output you want to get. Also show the code you are using to try to interpret this data.

There are lots of people here willing to help but you are going to have to be bit more clear about what you are looking for.

Also it would be better if you posted a reprex. See https://www.tidyverse.org/help/

If you are going to paste in R code directly always wrap it in

```{r}
 and 
```

As is we can’t just copy paste your code to try it out because all the quotes in it have to be edited