[R] interpreting significance of path coefficients from sem() output

[Michael Rennie]

Hi there,

Quick question about the output from the sem() function in the library 
of the same name.

If I am getting probabilities >0.05 for some of my estimates of path 
coefficients, I'm assuming the interpretation here is that the 
coefficient is not significantly different from zero, correct? In that 
case, might it make sense that I should disregard path coefficients 
between variables where the probability is greater than 0.05? In which 
case, would it make further sense to remove those particular links from 
the specify.model() command and re-run the analysis, excluding those 
rows which lacked significance in the previous attempt?

Given that in just about every other example I've been able to dig up 
where this method is employed (including other datasets I am working 
with), the probabilities of the path coefficients are almost always well 
below 0.05, it makes me suspect that what I am observing may simply 
result from the fact that I'm trying to fit a path analysis among 5 
variables (4 predictors, 1 criterion) based on only 18 observations, 
admittedly a small sample size and perhaps an overly ambitious approach 
to analyzing so few data.

Last, I'm convinced that I'm using the code correctly as I was able to 
successfully reproduce an example in Quinn and Keough (2002) before I 
turned the code onto my own data.

Looking forward to any thoughts or comments.

Cheers,

Mike

-- 
Michael D. Rennie
Ph.D. Candidate
University of Toronto at Mississauga
3359 Missisagua Rd. N. 
Mississauga, ON L5L 1C6
Ph: 905-828-5452 Fax: 905-828-3792
www.utm.utoronto.ca/~w3rennie