I am trying to create a function that will allow me to determine the number of
components to retain based on the results of the broken stick criterion. In
order to do so I know I need to compare the initial eigen values to the broken
stick eigen values. The initial eigen value which becomes lower than the
broken stick is the cutoff point so the cutoff for the number of components to
retain is the number of eigen values before this cutoff points.
So far this is the syntax I have and what I get.
ev <- eigen(cor(EFAexample))
ev
bstick(24, tot.var=24)
> ev
$values
[1] 7.2819381 2.3951299 1.8190170 1.6056666 0.9862474 0.9092235 0.8269931
[8] 0.7861644 0.6978157 0.6824547 0.6333925 0.5997783 0.5737571 0.5347758
[15] 0.4976710 0.4849214 0.4502025 0.4223273 0.3819080 0.3599697 0.3353226
[22] 0.3184069 0.2146300 0.2022866
> bstick(24, tot.var=24)
Stick1 Stick2 Stick3 Stick4 Stick5 Stick6 Stick7
3.77595818 2.77595818 2.27595818 1.94262484 1.69262484 1.49262484 1.32595818
Stick8 Stick9 Stick10 Stick11 Stick12 Stick13 Stick14
1.18310103 1.05810103 0.94698992 0.84698992 0.75608083 0.67274750 0.59582442
Stick15 Stick16 Stick17 Stick18 Stick19 Stick20 Stick21
0.52439585 0.45772918 0.39522918 0.33640566 0.28085010 0.22821852 0.17821852
Stick22 Stick23 Stick24
0.13059947 0.08514493 0.04166667
In this case the cutoff would be at stick 2 thus we would only retain 1
component. What syntax can I use to automatically make this comparison instead
of having to do it manually each time?
Also, am I using bstick correctly? From what I understand I should just have
to enter the number of components and the total variance which will be the
total number of components.
Any help would be greatly appreciated. Thanks!
Allyson
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