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An Alternative to Analysis of Covariance
You may find your error variables already positioned at the top of the path diagram,
with no room to draw the double-headed arrow. To fix the problem:
E From the menus, choose Edit > Fit to Page.
Alternatively, you can:
E Draw the double-headed arrow and, if it is out of bounds, click the Resize (page with
arrows) button. Amos will shrink your path diagram to fit within the page boundaries.
Results for Model B
Allowing eps2 and eps4 to be correlated results in a dramatic reduction of the
chi-square statistic.
You may recall from the results of Model A that the modification index for the
covariance between eps1 and eps3 was 9.788. Clearly, freeing that covariance in
addition to the covariance between eps2 and eps4 covariance would not have produced
an additional drop in the chi-square statistic of 9.788, since this would imply a negative
chi-square statistic. Thus, a modification index represents the minimal drop in the
Chi-square = 2.684
Degrees of freedom = 2
Probability level = 0.261
pre_verbal
pre_syn
eps1
1
1
pre_opp
eps2
1
post_verbal
post_syn
eps3
post_opp
eps4
1
1 1
treatment
zeta
1
Example 9: Model B
Olsson (1973) test coaching study
Model Specification