When calculating rates or trends, p-values are used in the calculation of confidence intervals and in significance testing. There are four p-values, one for each of the following calculations:
Confidence intervals for rates
Confidence intervals for APCs
Significance testing of APCs to 0
Significance testing of APCs to a base APC
The initial default value for all p-values is 0.05. This is equivalent to a 95% confidence interval or 0.05 significance.
To change any p-value, click Edit on the Statistic tab. The Level of Significance (P-values) dialog is displayed. You can change the values in the text boxes for Confidence Intervals and Significance Testing. The confidence intervals for rates and APCs are equal to 1 minus the p-value. The comparison between APCs to 0 or to APC is significant to the p-value.
Note that the p-value for rate confidence intervals can be edited during a Frequency session, but is only used during a Rate session.
If you use a certain set of p-values regularly, you may want to set them as the defaults. To do so, enter the desired settings in the appropriate text boxes and click Set Default. The new p-values will be the defaults whenever you create a Frequency or Rate session. The Defaults button can be used at any time to reset the individual p-values to the current defaults.
When you finish editing, click OK.