## Calculating Uncertainty 2 - Addition and Subtraction

This is the second of the set of videos on the assessment of total uncertainty in the final result. In this video, we learn to calculate the total uncertainty in addition and subtraction cases. In the next video, we will be calculating the total uncertainty in multiplication and division cases.

Link to the lesson "Calculating Uncertainty 1 - Absolute, Fractional, and Percentage Uncertainty": https://youtu.be/RUpDvNkIKLU

Link to the lesson "The Concepts of Least Count, Significant Figures, and Uncertainty": https://youtu.be/4tFMx6pQfbI

Link to the lesson "Rules of Significant Figures in Measurements": https://youtu.be/AhlMg2zpDa8

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This site provides links to random videos hosted at YouTube, with the emphasis on random.

The original idea for this site actually stemmed from another idea to provide a way of benchmarking the popularity of a video against the general population of YouTube videos. There are probably sites that do this by now, but there wasn’t when we started out. Anyway, in order to figure out how popular any one video is, you need a pretty large sample of videos to rank it against. The challenge is that the sample needs to be very random in order to properly rank a video and YouTube doesn’t appear to provide a way to obtain large numbers of random video IDs.

Even if you search on YouTube for a random string, the set of results that will be returned will still be based on popularity, so if you’re using this approach to build up your sample, you’re already in trouble. It turns out there is a multitude of ways in which the YouTube search function makes it very difficult to retrieve truly random results.

So how can we provide truly random links to YouTube videos? It turns out that the YouTube programming interface (API) provides additional functions that allow the discovery of videos which, with the right approach, are much more random. Using a number of tricks, combined some subtle manipulation of the space-time fabric, we have managed to create a process that yields something very close to 100% random links to YouTube videos.