Cash or Card: Consumer Perceptions of Payment Modes - Scholarly ...

6.3.3: Pre Test One- Internal Consistency Assessment
Reliability for internal consistency is based on correlations. The internal consistency of the
scale is evaluated via examining inter-item correlations, items-to-total and Cronbach alpha.
According to De Vellis (2003) internal consistency reliability is the measure of homogeneity
of the items within the scale. The logic is that the relationships among items are logically
connected to the relationships of the items to the latent variable; therefore, high inter-item
correlations suggest that items are all measuring the same thing. De Vellis (2003) and
Netemeyer, et al. (2002) suggest evaluating the item-to-total correlations for internal
consistency assessment. An item-total correlation test checks whether an item is consistent
with the average behaviour of the other items in the scale. A Pearson’s correlation below .30
indicates low correlation. The most common test for internal consistency is Cronbach’s
Alpha (Netemeyer, et al., 2003). Cortina (1993) cautioned not to apply alpha when assessing
dimensionality because interrelatedness of items within a scale does not imply
unidimensionality (the existence of one latent construct underlying a set of items) (Hattie,
1985). What constitutes minimum acceptable alpha level is debated, however, “a widely
advocated level of adequacy for alpha is.70” (Netemeyer et al. 2003, p.58). EFA and scale
reliability analysis shows that not all dimensions were equal or above 0.70 levels alpha but
overall average alpha value meets the acceptance (See Table 6.2).
The correlations within dimensions (positive emotions, negative emotions, control spending,
status/pleasure, money as gift and behaviour/usage) show all items are correlated moderately
(See Table 6.5). There is no clear guideline to what constitutes moderate inter-item
correlations. For example, Robinson, Shaver, and Wrightsman (1991) advocate average inter-
item correlations of .30 and Peterson (1994) ask for .31 and an overall average alpha of .80.
Clark and Watson (1995) consider average inter-item correlations of .15 to .50 across
construct to be acceptable. The items-to-total correlation (the correlation of the item and the
sum score of the other items) show all items within dimensions are internally consistent.
Correlations of less than 0.30 for item-to-total correlation are considered weak (de Vaus,
2004). The “behaviour/usage” factor shows weak correlations between the items, less than
.20 and below. These items were retained at this stage because they identified payment mode
perceptions.
95