The SD was taken from preliminary study (knowledge score control group), and 0.50 was selected as the value for effect size.
It might indicate that the basic knowledge of the control group was not less than that of the intervention group, and any significant increase in knowledge scores in the intervention group compared with the control group could then be considered as related to the intervention.
As a result, we tested hypotheses that (a) providers would have higher knowledge scores than patients and that (b) patients who had seen a decision aid would have higher knowledge than the control group, using two sample t-tests.
This suggests that the preferential effect of the intervention upon knowledge of the public health impact of depression had waned by six months, partly through increase in knowledge in the control group.
As illustrated in Table 2, there were significant increases in knowledge on HIV/AIDS transmission from baseline to post-test for the intervention groups, and no significant change in knowledge for the control group (t = 1.1, P = .92).92
The prior knowledge of the control group maybe also inferred to the experimental group.
Results showed that teachers who were provided training on psychosocial disaster preparedness had better knowledge than the control group.
The test group used the EAR method (including the Prolog processing system and SES) to create knowledge, while the control group used a text editor, the Prolog processing system, and SES to create Prolog code.
Yet a study of patients with hereditary colorectal cancer, who used educational materials like letters and booklets to understand their disease, did not show significant differences in knowledge compared to control group without the additional material (Gaff et al. [2005]).
Table 2 demonstrates that, using the mean change between baseline and three month follow-up, the intervention group had less increase in burden, a greater decrease in decisional conflict and a greater increase in knowledge compared with control group participants.
