Transactional vs. transformational leadership 2 5
A principal component factor analysis of the MLQ data was done to determine whether the factors as found by Bass would also be found in our data set. Again Cronbach's a and inter-item correlations were calculated. The aggregate measures for transformational, transactional and laissez-faire leadership as defined by Bass were correlated with each other and with the scales derived from factor analysis.
To assess the reliability and internal consistency of the scales several criteria were used. Items that did not meet the criteria were left out of subsequent analyses. This was done to increase the homogeneity of the scales. The criteria used in this study are those more often used in research and literature. The first criterion used is that the Cronbach Cf of the scale should be >.7O (Nunally, 1967). This seems to reflect the general idea in literature of what an acceptable Ct is. The criterion used for average inter-item correlations is that they should be >.3O. The criterion used in this study for item-rest correlations is that they should be >.20 (Kline, 1986). Criteria used for the factor loadings are: factor loadings should be >.3O and the difference between factor loadings of an item on two factors shold be >.2O. If items in the scales yielded by the factor analysis did not meet the criteria they were removed from the scales. Therefore rhe scales that were found and adapted in this study have fewer items than the scales as developed by Bass.
Results
The aggregate measures for transformational, transactional and laissez-faire leadership
The scale statistics for the dimensions of transformational, transactional and laissez-faire leadership as defined by Bass & Avolio (1989) are reported in Table 1. Transformational leadership was a high Cfof .93. Ho'wever, transformational leadership also has most items. The OS for the transactional (.60) and laissez-faire scale (.49) are below the .70 criterion.
The reason for the low a of the transactional measure is that passive management-by-exception is in Bass' transactional scale, even though the findings of the present study show that correlations between passive management-by-exception and the other transac-tional dimensions are negative. When passive management-by-exception is left out of the transactional scale, the a of transactional leadership increases to .79 (this scale would have eight items).
Table 1. Scale statistics for Bass' theoretical scales
I Transformational leadership:
lA items a = .95
Mean = 3.03
SD = .33
average inter-item correlation .44 (variance = .02) range ofitem—total correlation .32 to .77 II Transactional leadership:
12 items a= -60
Mean = 2.48
SD = .62
average inter-item correlation .12 (variance = .06) range of item-total correlations —.07 to .46 III Laissez-faire leadership:
4 Items a = -49
Mean = 2.34
SD = .59
average inter-item correlation .21 (variance = .04) range of item-total correlations .09 to .44
26 Deanne N, Den Hartog, JaapJ, Van Muifen and Paul L, Koopman