Histograms03:52 minutes

Video Transcript

TranscriptHistograms

Jaques has decided to raise his profile as a restaurant critic with an exposé on restaurant pricing practices. To research, he's been gathering data on 20 carefully-selected restaurants, and he's saved the best for last - the hippest place in town to eat. Jaques plans to publish his findings using histograms.

Setting up a histogram

In the very trendy restaurant, Jaques discovers the prices range from 6 to $28. He refers to the prices down in the menu. He'll use the restaurant's menu to make his histogram. So after he enters the price data in his app, Jaques chooses the number of meals on the vertical axis of his histogram. And on the horizontal axis, he divides the range of entrée prices into intervals, which are also called bins. The first interval, or bin, is 1 to$10, the next bin is 11 to $20, and so on. The bins must not overlap, and they must be of equal size. ’s menu has 2 items that cost 1 to$10, five items that cost 11 to $20, and three items that cost 21 to$30.

As you can see, a histogram looks like a bar graph; but with a histogram, each bar represents a range of values rather than a single value. Histograms are a good choice to display data such as heights, weights, elapsed time, and prices. You get the idea.

Interpreting the intervals

To present the information clearly, it’s important to title and label your graph. A histogram may make data easier to analyze than if the same data were presented in a list. But, what if we change the intervals? Jaques increases the number of bins and decreases the range of each bin. This histogram presents the same data but displays smaller intervals. From this graph, you might conclude that the menu has a fairly even distribution of the price range for all the meals. So, keep in mind, when you create and interpret histograms, the size of the intervals can impact the interpretation of the data.

Jaques also collected the data on the number of meatballs served per dish of spaghetti. There is quite the range of meatballs on top of spaghetti - take a look. Some restaurants serve only 1 meatball in a single serving while others serve up to 15. From this histogram, we can conclude that most of the restaurants surveyed normally dish out 4 to 6 meatballs per entrée. Remember, when you create and interpret histograms, the size of the intervals can impact the interpretation of the data.

But we don’t know the cost of the meals or the size of the meatballs, so what do we really know? If Jaques only had three bins, he might have interpreted the restaurant’s pricing differently.

Summary

So, not only have you learned some sensational information about restaurants, you have also learned about histograms. Just like restaurants, there may be more to histograms than meets the eye. When creating and analyzing histograms, pay attention to the intervals also knows as bins. Be aware they can affect the appearance of a histogram and any resulting conclusions.

Jacques is finished with his investigation and his meal. Oh no, he forgot his wallet! I guess he’ll have to wash the dishes!

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