Proceedings

variance inflation factor (VIF). The variance inflation factor (VIF) quantifies the
severity of multicollinearity in an ordinary least squares regression analysis. The
highest VIF is 2.239. Hence, collinearity did not appear to be a serious problem in
interpreting the regression results.).
Table 6. Correlation Matrix with Overall Disclosure Index
Index
ALL
Size Leverage Age ROA Liquid.
Innovativeness
Index
ALL
1.000
Size 0.127 1.000
Leverage -
0.220
0.334* 1.000
Age -
0.101
0.470** 0.239 1.000
ROA 0.130 0.079 -0.434** 0.208 1.000
Liquid. 0.162 -0.302* -0.587** -0.034 0.220 1.000
Innovativeness
0.366* -0.285* -0.231 -0.187 -0.069 0.115 1.000
~ 750 ~
Auditor
Auditor 0.115 0.471** 0.102 0.272 0.112 0.096 -0.190 1.000
*. Correlation is significant at the 0.05 level (2-tailed).
**. Correlation is significant at the 0.01 level (2-tailed).
Multiple regression analysis was used to answer the question if there is an influence
of several firm-specific characteristics on the extent of voluntary disclosure over all
disclosure items in XBRL (the dependent variable in the analysis). Moreover,
regression analysis was performed for the three information subgroups as dependent
variables in order to assess factors explaining the extent of disclosures within the
subgroups. Thus, the study ran four regressions. Table 7 reports the model summaries
for the overall voluntary disclosures and for each of the three information subgroups.
The results are statistically significant both on an overall basis (10%-level) and by
financial information type (5%-level), whereas the statistical model of the
subcategories non-financial and general information is not significant. Table 7
indicates adjusted R2 of 16.6% (F-ratio 2.426, p=0.035), which shows that a moderate
percentage of the overall disclosure index as the dependent variable can be explained
by variations in the entire set of independent variables. Premuroso and Bhattacharya
(2008) reported in their empirical study about voluntary XBRL filers a higher
adjusted R2 of 0.333, but with a smaller sample of firms and less independent
variables. Compared to the empirical literature in voluntary disclosure, lower adjusted
R2 statistics were reported by Wallace (1988) at 0.07, whereas higher adjusted R2
statistics were reported by Wallace et al. (1994) at 0.6050, Ahmed (1995) at 0.332,
and Camfferman and Cooke (2002) at 0.193 (This value is for the Dutch sample. For
the UK sample an adjusted R 2 of 0.231 was reported.). The amount of explained
variation in disclosure subgroups ranges from 18.3% in the case of financial
information to 7.3% for general information, with non-financial information in
between at 6.7%.