2007 Annual International CHRIE Conference & Exposition
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Table1
Comparison of Overall Fit Indices for Proposed and Modified Models (N = 198)
Model
χ
2
Df
Χ
2
/
df
NNFI CFI RMSEA
Δ
χ
2
Model A
a
1209.1 681 1.78 .827 .841 .063
-
Model B
b
391.2 278 1.41 .931 .941 .045
817.9
*
Note: NNFI = non-normed fit index; CFI = comparative fit index;
RMSEA = root mean square error of approximation;
Δ
χ
2
=
χ
2
difference
between two models (i.e.,
χ
2
of Model 1 minus
χ
2
of Model 2 = 562.3)
a
Model A: Initial model containing 39 items derived from the exploratory
factor analysis.
b
Model B : Model A minus (V1, V2, V5, V6, V12, V13, V14, V20, V24, V25, V27, V34).
In the first step, a proposed measurement model (Model A) obtained from EFA was tested. According to
overall fit indices, the proposed model did not produce a good fit with the data,
χ
2
(681) =1209.1, p<.001
(
χ
2
/df=1.78, CFI = .82, NNFI = .80, RMSEA = .06) in this initial step. The initial model labeled as model A does not
show acceptable fit indices (CFI = .827 and NNFI = .841), although its chi-square ratio (< 3) and RMSEA (< .10)
are in acceptable ranges. Thus, the proposed model needed further modifications. When the proposed model was
required for the improvement in fit –in other words, the fit was found to be inadequate - modification procedures
were conducted to identify candidate observed variables for deletion from the measurement model. These
procedures are customary to maximize the fit (Bollen, 1989). Thus, the model modification procedures proceeded to
identify observed variables that had low factor loadings, significant cross-loadings, and large residuals using
standardized factor loadings. The MI test objective was to determine whether, in subsequent runs, models would
better represent the data, with certain parameters specified as free rather than fixed. As the minimum cut-off, it was
suggested that a standardized factor loading should be greater than .50, and each MI should not exceed 100 (Kline,
1998). AMOS provided three measures. After removing observed variables based on three criteria, overall fit
measures (CFI, NNFI, RMSEA, and
χ
2
difference test) were used iteratively to determine whether the CFA model
fitted data well.
In the second step, thirteen observed variables were identified with low factor loadings (below suggested
level of .50 for the expected constructs.), shared factor loadings, and shared large residuals with other observed
variable loadings (above MI suggested level of 100). Thus, those variables were removed for modified model
(Model B). Model B was re-estimated. Results from running this model showed that all fit indices suggested a good
fit of data,
Δ
χ
2
(278) = 391.2, p<.01,
χ
2
/
df
= 1.4, CFI = .941, NNFI =.931, RMSEA = .045. The modified model
surpasses the proposed model on all fit criteria, which confirmed that the modifications were meaningful. Through
this process to assess a model’s fit, modified model of
experience
(Model B) resulted in seven factors (26 items)
distributed as follows: Sales environment (7 items), Driving Benefit (4 items), Shopping Convenience (3 items),
Accessibility (4 items), Utility (3 items), Incentive (3 items), and Brand Trust (2 items) as shown in Table 2. The
modified final CFA model has the
same factor structure with seven factors as does the EFA factor model. It is
purified from EFA model (39 items to 26 items).
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