dis15

Background Info: On Feb. 28, the stock market had its largest loss since the 2008 financial crisis. By April 11, more than 22 million Americans had lost their jobs. By May 27, 100,000 Americans had died from Covid-19. Note that these are all counts, not percentages.And the airline industry? In a typical year, April and May have, on average, about 2.4 million air travel passengers per day. But, for the week ended April 17, 2020, the count was only 95,161 per day. The week ended May 17, the count was 212,580 per day. The May count was only a slight recovery, but the percentage change makes it seem like a surge. The headline “Air Travel Surges 123%!” is accurate, but is it misleading? In this activity, you will learn that even when percentage change is calculated accurately, it may give misleading impressions. This happens especially when the data values vary significantly. With these insights, you will better know when it is appropriate to use percentage change to describe growth and when it may be better to use counts to describe change.

Step 1: Read Air Travel Surges by 123%! (Beware of Misleading Data Like That).

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Step 2: Create your first post by Wednesday Your post needs to be a minimum of 200 words. Respond to one or two of the following questions:

1. The article states that growth rates (percentages) or levels (counts) can both be accurate. However, when there are big swings in data, the growth rates can be misleading. According to the article, how could politicians use the difference in growth rates and levels to their advantage?

2. The authors state: “When something falls by 10 percent and then rises by 10 percent, it might seem as if it ends up back where it started. But that’s not how the math works.” Calculate where it ends up. Why doesn’t it end up back where it started?

3. The headline of the print version of this article is “Air Travel Surges 123% (Beware a Data Yo-Yo).” Describe the yo-yo that is referred to in that headline. This excerpt from the article may help you:

A 10 percent drop from 100 to 90, followed by a 10 percent gain, would return it only to 99. With bigger swings, those effects become more striking. A 40 percent drop followed by a 40 percent gain would result in a quantity 16 percent below the starting point.

At even greater extremes, you end up with bonkers numbers like those in the air traffic example, in which a 96 percent drop followed by a 123 percent gain leaves you with a number that is still 91 percent below normal.

Use 100 as your starting point. Apply the air travel percentage changes to confirm the 91 percent below normal “yo-yo” effect. What in the arithmetic makes the “yo-yo” effect happen? What should be reported in an article to clarify what is really happening to air travel?

4. The article concludes with some advice: “more than anything, it means thinking carefully about what a given number really means, and not just taking a seemingly breathtaking percentage change at face value.” What do you think it means to not take a “breathtaking percentage change at face value”?