Talk:Factor analysis/Archives/2018

Contradictory statements about variable indexes?

'"Subject" indices will be indicated using letters a,b and c, with values running from 1 to {\displaystyle N_{a}} N_{a} which is equal to 10 in the above example. ... "Instance" or "sample" indices will be indicated using letters i,j and k, with values running from 1 to {\displaystyle N_{i}} N_{i}. In the example above, if a sample of {\displaystyle N_{i}=1000} N_{i}=1000 students responded to the {\displaystyle N_{a}=10} N_{a}=10 questions, the ith student's score for the ath question are given by {\displaystyle x_{ai}} x_{ai}.'

These statements appear to me (a novice) to be contradictory; we say student indices are a, b, c then proceed to say that there are N_i = 1000 students, not N_a students. Using i, j, and k for students also seems to happen in the paragraphs following this one. Someone who knows what they are doing should confirm this and clean it up. — Preceding unsigned comment added by DanAtPearson (talk • contribs) 17:34, 30 January 2017 (UTC)

Your confusion is probably due to identifying two words which are different: the quote says "subject", not "student". The article text seems perfectly fine in this respect. 130.243.68.90 (talk) 13:10, 8 March 2017 (UTC)

Similar confusion could arise in the definitions following the statement of the derivation of $z$_ai. It is correctly stated that $l$_ap is the coefficient for subject matter "a" and it is being applied to the factor $F$_pi from student "i", but the word "subject" is used to indicate the experimental unit in so many behavioral studies (in the example, student is the experimental unit) that it might help to state this all explicitly. — Preceding unsigned comment added by Markssss (talk • contribs) 22:45, 20 November 2018 (UTC)