Supervisión y seguimiento a la Ejecución de los contratos

H10a: There is a significant difference between the proportions of information search in

the GIS-MCDA individual and group modes. The null hypothesis is that the decision

mode has no influence on the proportion of information search. The hypothesis was tested by comparing the mean proportion of information searched in the two decision modes. The comparison illustrates that this metric is higher in the individual mode than that in the group mode (see Figure 27). For the effect of the decision mode, the LMM test results

125

give a p-value of 0.010 (F =7.24, p =0.010 < 0.05), thereby rejecting the null hypothesis and suggesting there is a statistically significant difference in the proportion of information searched between the two decision modes. In other words, there is sufficient evidence from the data to conclude that decision makers search a significantly different proportion of the available information in the GIS-MCDA individual mode as compared to the group mode. This is consistent with the findings reported by Schrah et al. (2006) that the information acquisition strategies differ between the decision situations where recommendations are provided (advice acquisition ) and those where they are not. They found that recommendations concerning the choice of one or more specific alternatives affect the information acquisition strategies (e.g., the proportions of information search) used by the decision makers (see also Bonaccio & Dalal, 2006). Consequently, it is likely that the representation of the group/consensus ranking of alternatives as the choice recommendations influence the way that participants acquire and integrate information in their individual decisions.

Figure 27. A comparison between the proportions of information search in the two decisions modes.

126

H10b: The difference in the proportion of attribute ranges searched between the GIS-

MCDA individual and group modes is significant. The null hypothesis states that the

decision mode has no impact on the proportion of attribute ranges searched. By comparing the proportion of attribute ranges searched in the two decision modes, it is evident that this variable in the individual decision mode is higher than that in the group mode (see Figure 28). The LMM test results suggest that the null hypothesis of no difference between the two decision modes in terms of the proportion of attribute ranges searched should be rejected (F = 16.92, p = 0.001 < 0.05). Therefore, one can conclude

that there is a significant difference in the proportion of attribute ranges examined between the two decision modes.

Figure 28. A comparison between the proportions of attribute ranges searched in the two decisions modes.

H10c: The amount of average time spent on each piece of information acquired is

significantly different between the two decision modes. The null hypothesis is that the

amount of average time spent on each piece of information is not affected by the decision mode. By comparing the average decision time between the two decision modes in the four experimental conditions (see Figure 29), one can indicate that the time spent

127

acquiring the information pieces in the individual mode is more than that in the group mode. Under the null hypothesis that there is no difference in the average decision time between the two decision modes, the LMM test gives a p-value of 0.033 (F = 5.04, p

=0.033 < 0.05). This suggests that there is a significant difference in the average decision time between the two decision modes.

Figure 29. A comparison between the average decision times in the two decision modes. H10d: There is a significant difference in the variability of information search per

attribute between the GIS-MCDA individual and group decision modes. The null

hypothesis states that the two decision modes are not significantly different in terms of the variability of information searched per attribute. Comparing the mean variability values of the information searched between the two modes indicates that the variability is higher in the individual mode as compared to the group mode (see Figure 30). The results indicate that there is a statistically significant difference in the variability of information searched between the two modes of GIS-MCDA. For the decision mode effect, the LMM test gives a p-value of 0.047 (F =4.63, p = 0.047 < 0.05), thereby suggesting that we

reject the null hypothesis, or alternatively that the decision mode has an insignificant impact on the variability of information searched per attribute. These findings are consistent with the suggestion by Schrah et al. (2006), that recommendations regarding which alternative to choose have an influence on thevariability of information search per

128

attribute. Consequently, the group recommendations regarding the rankings of decision alternatives significantly affect the variability of information search per attribute.

Figure 30. Comparing the variability of information search per attribute in the two decisions modes.

H10e: There is a significant difference in the variability of information search per

alternative between the GIS-MCDA individual and group decision modes. The null

hypothesis is that the decision mode has no influence on the variability of information search per alternative. Figure 31 shows a comparison of information searched per alternative between the two decision modes in each of the four decision situations. A comparison of the mean variability values in the two decision modes indicates that the variability is pretty much the same in the two decision modes. This is confirmed by the LMM results, indicating that the observed difference in the variability is not statistically significant (F = 1.47, p = 0.233). Thus, this hypothesis is not supported by the evidence

129

Figure 31. A comparison between the variability of information search per alternative in the two decision modes.

H10f: The direction of information search is significantly different between the GIS-

MCDA individual and group decision modes. The null hypothesis states that there is no

difference between the directions of information search in the two decision modes. Participants were expected to adopt different information search directions when the decision mode was changed. Comparing the SI and SM mean values in the two modes suggests that the participants used different search patterns in the two decision modes (see Figures 32 and 33). The LMM results for differences in the direction of information searched between the two decision modes gives a p-value of 0.570 (F = 0.32, p = 0.570)

and 0.421 (F = 0.67, p = 0.421) for SI and SM, respectively. This implies that the null hypothesis of no difference cannot be rejected (or the decision mode has an insignificant impact on the directions of information search). It provides evidence that the direction of information search in the individual decision mode is insignificantly different from that in the group decision mode. The result contradicts Schrah et al. (2006) findings. In their research, the effect of advice acquisition (choice recommendation) on search pattern was found significant at the low and medium complexity levels, and insignificant at the high level of task complexity. The possible reasons for the discrepancy between the findings of

130

this study and Schrah et al. (2006) findings might be those discussed with reference to H3a .

Figure 32. A comparison between the directions of information search (SI index) in the two decision modes.

Figure 33. A comparison between the directions of information search (SM index) in the

131

H10g: There is a significant difference in the total time spent acquiring information in the

decision table between the GIS-MCDA individual and group decision modes. The null

hypothesis states that the decision mode has no influence on the total time spent acquiring information in the decision table. It was expected that the difference in the total time

between the two decision modes would be significant. A comparison of the mean times in the two modes confirms that the participants spent different amounts of time in the two decision modes (see Figure 34). Given the null hypothesis of no difference in the total time between the two decision modes, the LMM test gives a p-value of 0.000 (F = 34.86, p = 0.000). This suggests that the null hypothesis of no difference in the total time should

be rejected, meaning that the total time spent in the individual decision mode is significantly different from that in the group mode.

Figure 34. A comparison between the total times spent acquiring the information in the two decision modes.

H10h: The total time spent on the map is significanttly different between the GIS-MCDA

individual and group decision modes. The null hypothesis is that the total time spent on

the map is not influenced by the decision mode. By comparing the mean times for the two modes in the four experimental conditions, it becomes clear that the total time spent on the map in the individual mode differs from that in the group mode (see Figure 35). However, under the null hypothesis that there is no difference in the decision times

132

between the two decision modes, the LMM test gives a p-value of 0.168 (F = 1.95, p = 0.168). This suggests that there is an insignificant difference in the decision time spent on the map between the decision modes. The lack of significant difference may be, in part, due to the fact that the decision makers focus more on the decision table than the map. In other words, the use of a map in the two decision modes is insignificant, and therefore the difference is intangible.

Figure 35. A comparison between the total times spent on the map in the two decision modes.

H10i: There is a significant difference in the number of map moves between the two

decision modes. The null hypothesis states that the decision mode has no significant effect

on the number of map moves. A comparison between the number of map moves in the two decision modes is shown in Figure 36. For the decision mode effect, the LMM test gives a p-value of 0.722 (F = 0.12, p = 0.722), thereby suggesting that the null hypothesis

of no difference in the total map moves should be accepted. Thus, the hypothesis has not been supported by the evidence.

133

134