the phone company stopped using letters in mid-1960s.
the phone company stopped using letters in mid-1960s.
when did the phone company stop using letters?
mid-1960s
Na
Na
in the following, matrices will be indicated by indexed variables. "subject" indices will be indicated using letters a,b and c, with values running from 1 to formula_35 which is equal to 10 in the above example. "factor" indices will be indicated using letters p, q and r, with values running from 1 to formula_36 which is equal to 2 in the above example. "instance" or "sample" indices will be indicated using letters i,j and k, with values running from 1 to formula_37. in the example above, if a sample of formula_38 students responded to the formula_39 questions, the "i"th student's score for the "a"th question are given by formula_40. the purpose of factor analysis is to characterize the correlations between the variables formula_41 of which the formula_40 are a particular instance, or set of observations. in order for the variables to be on equal footing, they are normalized:
factor analysis