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**Road Map**

Demand can vary widely; not only over the course of the year, but throughout a day. Understanding how demand changes from one hour to the next is important for resource adequacy and is the focus of deterministic resource adequacy.

Probabilistic resource adequacy focuses on the variability from what is expected at a given moment. This is done by analyzing distributions of all possible values and the probability that each value will occur. Although the peak of the distribution is the expected value for that hour, the range of possibilities can be great. This shows the uncertainty of expectations in a given hour.

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**Page Tip**

Clicking a region on the map will change the charts to show that area's information. Clicking the same area again will switch the charts back to the overall Western Interconnection results.

Click one of the low-margin days on the scatter plot. The following chart will show the hourly expected profile for that day.