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API CAN CODE �Data Science Practices

Lesson 3.3: Graphs and Figures for One Variable

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This work was made possible through generous support from the National Science Foundation (Award # 2141655).

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Warmup

  • Examine the graph to the right.�
  • What kind of graph is this?�
  • What variable(s) do you see represented? Is there more than one? �
  • What do you notice? �What do you wonder?�
  • What story does this graph portray?

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Lesson 3.2 Recap

  • In Lesson 3.2, we learned some of the basics of using CODAP, including quickly generating some graphs using click-and-drag to visualize data�
  • These graphs can help us understand data distributions as well as the relationships between different variables�
  • Today, we’ll hone in on graphs and figures in one variable

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Seal Tracking

Watch the video and answer:

  • Why is this work important?
  • What could we use this data for?
  • What kinds of data do you think we collect from the seals?

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Four Seals - CODAP Dataset

  • Open the Four Seals example in CODAP.
    • What kind of data is this?
    • What’s going on in this dataset?
    • What do you notice? What do you wonder?

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Four Seals - Mapping the Data

  • Open the Four Seals example in CODAP.
    • Drag “animal_id” �onto the map and �see what happens. �
    • What does this help �you understand?

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Four Seals - Comparative Dotplot

  • Drag “animal_id” onto the y axis and “depth” onto the x axis to create a comparative dotplot. You should see data divided by seal.

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  • Answer the questions in the following slide.

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Four Seals - Interpreting the Data

  • Answer the questions:
    • What does each dot represent? Why are there four dotplots? What does it mean when lots of dots are stacked on top of each other?
    • Which seal would you say tends to swim deepest? (You may want to click the Ruler icon, and check a box to show Mean, Median, or other metrics.)
    • Look at the different shapes of the four dotplots. What is unusual about seal 546? How would you describe the shape of seal 541’s distribution?

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Four Seals - Box Plot

  • Click the Ruler icon and check “Box Plot.”
    • Where do the “whiskers” of the box plot end?
    • Can you see individual data values in the box plot like you can on the dotplot?
    • Go back in to the Ruler icon menu and click “Show Outliers.” Are there any outliers? How do you think the program makes the decision to mark certain points as outliers or not?
    • (More notes on boxplots here!)

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Median

Q1

Q3

max

min

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Four Seals - Skewness

  • Now, create a new graph. Drag “speed” onto the x-axis to create a single dotplot.
    • What shape does this dotplot have? Is it symmetric? Skewed to the left? Skewed to the right?

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Skew is a measure of how asymmetric a graph is. A graph with a left skew has a long, low left tail, whereas a graph with a right skew has a long, low right tail.

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Four Seals - CODAP Dataset

  • Now, create a new graph. Drag “speed” onto the x-axis to create a single dotplot.
    • Where would you say the center of the speed variable rests? (You might use the Ruler icon to find the Mean or Median. Are they the same? Different?)
    • How much spread is there to this data? (You might use the Ruler icon to add the standard deviation or IQR.) How much does the average speed vary from the mean speed?

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Four Seals - Measures of the Center

  • Still working with the new speed graph, go to the Graph icon and “Group Into Bins,” then go back to the Graph icon and “Fuse Dots Into Bars.”
    • What you see now is called a histogram – a summary plot for a set of data that organizes data points into “bins.”
    • Can you see individual data points in a histogram?
    • Why would a histogram be useful? �
      • (More on histograms here!)

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Histograms vs. Bar Charts

Histograms and bar charts/graphs summarize different kinds of data. �

What differences do you see in the data displayed in these two graphs?�

(Hint: what kind of variables are displayed in each x-axis?)

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(More on bar charts here!)

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Histograms vs. Bar Charts

Histograms are used to summarize counts of quantitative variables, while bar charts/graphs summarize counts of qualitative variables.�

The graph to the right is not a histogram. How can you tell?

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Histograms vs. Bar Charts

Would a histogram or bar graph be better for displaying each variable’s distribution? Why?

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  • different dog breeds at a particular dog daycare�
  • scores on the SAT for a class of high school seniors�
  • species of birds encountered on a walk around a local pond�
  • monthly rent cost at different apartments in the DC area

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Exit Ticket

In CODAP, create a new graph by dragging “temperature” onto the x-axis. �

What kind of graph is this? �

Would this data be displayed with a histogram or a bar graph?�

What is the mean temperature? (Hint: use the Ruler icon!)

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Thanks!

apicancode@umd.edu

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This work was made possible through generous support from the National Science Foundation (Award # 2141655).