1. Displaying Quantitative Data
Ch. 4
Displaying Quantitative Data

2. Discuss with your group: “What do you think will be different in charts that display quantitative data compared to categorical data?”
Warm-Up

3. Histograms look a lot like bar charts but are used for quantitative variables! Make sure to pay attention to the differences while watching this video: D1mYpU
Histograms

4. For histograms, slice up the entire span of values covered by the variable into equal-width sections called bins
Replacing the counts with % is called relative frequency histogram

5. “I feel the pressure, under more scrutiny, and what I do
“I feel the pressure, under more scrutiny, and what I do? Act more stupidly. bought more jewelry, more Louis V, my momma couldn't get through to me.” - ???

7. Money made from Kanye’s albums in the U. S

8. You can also create histograms with graphing calculators! (p. 54)

9. Grades
Frequency
60s 2
70s 4
80s 7
90s 5
100 1

11. Stem-and-Leaf Display
Stem-and-Leaf plots contain all the information found in histograms but displayed differently
Stem-and-Leaf Display

12. What if the data are not numbers with a tens and ones digits. i. e. 1
KEY: 1|5 = 1.5

13. What about big numbers such as 210,350,300,290,440?
KEY: 2|1 = 210 , 2|10 = 210

15. We can use stem and leaf plots to compare data collected from two groups.
How?
Comparing Two Groups

17. A dotplot is a simple display that places a dot along an axis for each case in the data
Dotplots

19. Split into halves like usual and record data for each person’s shoe size (in cm) in your group.
Create ??? that represents this data. (Make sure everyone keeps this data, we will be using it in the future!)
Class activity

20. What are the advantages of each of these graphs: histogram, stem and leaf plot, and dotplot?

21. What is the Center?

22. After drawing a histogram for our data, we want to describe the distribution
Three things to look at: shape, center, and spread
Shape, Center, & Spread

23. Shape

25. Humps on a graph are called modes, graphs can be unimodal, bimodal, or multimodal
If all data on a graph are the same height, than it is uniform

28. Graphs can be symmetric
If not, more data values lie on one side of the middle
Tails are the thinner ends of a distribution
If one tail stretches out further than the other, the graph is said to be skewed towards the long tail

29. Outliers are data values that stand off from the body of the distribution
They can affect the measurements of data significantly, so it is always important to identify them
Cont.

31. Finding the center of a graph may not always be simple, depending on the shape
What is the easiest graph shape for locating a center?
Center

32. Describing spread involves looking if the data is tightly clustered around the center or spread out
Spread will be expanded on in later chapters
Spread

33. Comparing Distributions
A lot of times, comparing two or more distributions can be very interesting (i.e. salaries of jobs in the medical field vs. engineering)
Look at the center, shape, and spread of each distribution to compare
Comparing Distributions

35. When data is collected in a specific order (i. e
When data is collected in a specific order (i.e. years), there may be patterns
Use timeplots to observe any noticeable patterns/behavior
Timeplots

37. We can make a skewed distribution more symmetric by re-expressing the data
There are many ways of re-expression such as taking the square root or logarithm of each data value
Improving Symmetry

38. Cont.

39. https://www.youtube.com/watch?v=Lrgp KjiQbQw