Contrast Results

This table displays results for each contrast. Simple contrasts using the first level of Clot-dissolving drugs as the reference category were specified. Thus, one contrast compares the second level to the first level; that is, the effect of reteplase to the effect of streptokinase. The contrast estimates show that, on average, patients given reteplase spend 0.382 fewer days in the hospital and incur almost 600 dollars more in treatment costs than patients given streptokinase. Since the significance value for Length of stay is less than 0.05, you can conclude this difference is not due to chance. The significance value for Treatment costs is greater than 0.10, so this difference may be entirely due to chance variation. The second contrast compares the third level to the first level; that is, the effect of alteplase to the effect of streptokinase. The contrast estimates show that, on average, patients given alteplase spend about half a day less in the hospital and incur slightly over 700 dollars more in treatment costs. Since the significance value for Length of stay is less than 0.05, you can conclude this difference is not due to chance. The significance value for Treatment costs is greater than 0.10, so this difference may be entirely due to chance variation.

The contrast results show that alteplase and reteplase seem to reduce patient length of stay. Moreover, the reduction is enough to equalize the treatment costs, or at least bring the difference within the random variation. Thus, the model suggests that alteplase and reteplase should be used in place of streptokinase. However, before adopting this plan, you should check some tests of the model assumptions.

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