Using this simple R code, I have performed a factor analysis on my dataset:
factanal(df, factors = 6, scores = "regression", rotation = "varimax")
I have now found significant factors that I want to keep. I also have chosen to generate scores using the "regression" argument. I'm still not clear on all the steps
factanal uses to provide the scores, but after some digging, I found that the "regression" argument does use what is known as Thomson's regression to generate some score. That score then seems to be turned into a z-score given all the scores.
So here is the question: Let's say that some new data comes in and I want to be able to give it a score as well. This new data happens to be one individual sample (the equivalent of one row of a new dataset).
Is there a proper way to give an individual sample a score or must the scores be generated on a population basis?