Hello All,
it's been a while since I posted something.
I'd like to have some insights on the interpretation of a LDA biplot I am working with.
I have run LDA in R, using MASS::lda(), on a dataset made up by a number of clay samples from 3 geographical areas; the predictors are 9 oxhides coming from a larger body of oxhides whose concentration has been measured and reported in %. The sub-compositional dataset has been log10 transformed before running lda.
I understand that in LDA the Discriminant Functions are linear combinations of the predictors that aim at maximizing the group separation. Now, giving a look at both the LDA biplot (LINK) and to the coefficient of linear discriminant (LINK), I am wondering:
Gm
p.s.
I have added LINKs to my dropbox coz I had issues in uploading attachments
it's been a while since I posted something.
I'd like to have some insights on the interpretation of a LDA biplot I am working with.
I have run LDA in R, using MASS::lda(), on a dataset made up by a number of clay samples from 3 geographical areas; the predictors are 9 oxhides coming from a larger body of oxhides whose concentration has been measured and reported in %. The sub-compositional dataset has been log10 transformed before running lda.
I understand that in LDA the Discriminant Functions are linear combinations of the predictors that aim at maximizing the group separation. Now, giving a look at both the LDA biplot (LINK) and to the coefficient of linear discriminant (LINK), I am wondering:
- Am i correct in concluding that LD1 manages to discriminate between the black group to the left-hand side and between the two groups to the right?
- ...and that LD2 discriminates (albeit with some "issues") between the green and the red groups?
- How to interpret the coefficients of linear discriminant? I understand that they "give an idea" of the importance of the predictors in the determination of the LDs; am I right?
- Is there an objective way to single out the "most important" ones?
- How to correctly interpret the direction, length, and position of the predictors' vector both in relation to the LD axis and to the observation data points?
Gm
p.s.
I have added LINKs to my dropbox coz I had issues in uploading attachments
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