chapter 2 section 2.1: organizing qualitative data section 2.2: organizing quantitative data section...
TRANSCRIPT
Chapter 2
• Section 2.1: Organizing qualitative data• Section 2.2: Organizing quantitative data• Section 2.3: skip• Section 2.4: Misrepresentations of data
Qualitative vs. Quantitative (Different tools for different data)
• Question 1: Type of skin cancer– A: Qualitative– B: Quantitative
Qualitative vs. Quantitative (Different tools for different data)
• Question 1: Type of skin cancer– A: Qualitative– B: Quantitative
• Question 2: Quarterly profit – A: Qualitative– B: Quantitative
Qualitative vs. Quantitative (Different tools for different data)
• Question 1: Type of skin cancer– A: Qualitative– B: Quantitative
• Question 2: Quarterly profit – A: Qualitative– B: Quantitative
• Question 3: Customer satisfaction– A: Qualitative– B: Quantitative
Qualitative vs. Quantitative (Different tools for different data)
• Question 1: Type of skin cancer– A: Qualitative– B: Quantitative
• Question 2: Quarterly profit – A: Qualitative– B: Quantitative
• Question 3: Customer satisfaction– A: Qualitative (poor, moderate, high)– B: Quantitative (1,2,3,4,5,6,7,8,9,10)
It isn’t always totally clear!
• Frequency: A fancy word for “count”
• Frequency: A fancy word for “count”• Distribution: A way to describe how likely
certain values are to be observed.
• Frequency: A fancy word for “count”• Distribution: A way to describe how likely
certain values are to be observed.• Frequency distribution: A list tabulating the
number of occurrences for each category
• Frequency: A fancy word for “count”• Distribution: A way to describe how likely
certain values are to be observed.• Frequency distribution: A list tabulating the
number of occurrences for each category• Relative frequency distribution: A frequency
distribution that uses proportions instead of counts.
Which is a relative frequency table?Statistics 108 students’ class standings (n=79)
Class standing
Freshmen 0.5000
Sophomore 0.1500
Junior 0.1750
Senior 0.1625
A
B
SophomoreSeniorJuniorFreshman
50
40
30
20
10
0
Class
Perc
ent
Stat 108 students
Percent within all data.
These graphs are:(A)bar graphs (B)histograms
Which graph is the relative frequency graph? (A) top graph(B) bottom graph
• The only difference between a frequency bar graph and a relative frequency bar graph is the labeling of the y-axis. (Likewise for histograms.)
• Relative frequency saves the reader calculations
• Frequency graphs tell the reader the actual counts.
A pie chart of the data
Fr
So
Jr
Sr
Use the below data to calculate degrees of the sophomore slice.
(A)12 degrees(B)0.15 degrees(C)15 degrees(D)55 degrees
Histograms
• Histograms are for quantitative data• “Classes” or “bins” are which data are
grouped into.• Upper and lower limit for each class/bin is
subjective.• Goal: Summarize data, but leave some detail.
Histograms of sparrow weights
Moderate number of bins
Fre
qu
en
cy
22 24 26 28 30 32
01
02
0
lots of bins
Fre
qu
en
cy
22 24 26 28 30 32
05
10
15
Weights of 87 sparrows (grams)23.2 23.3 23.3 23.5 23.6 23.7 23.8 23.9 24 24.1 24.2 24.3 24.3 24.3 24.4 24.5 24.6 24.6 24.6 24.6 24.7 24.7 24.7 24.8 24.8 24.9 24.9 24.9 25 25 25 25.1 25.4 25.5 25.5 25.6 25.6 25.6 25.7 25.7 25.7 25.7 25.7 25.8 25.9 25.9 26 26 26 26 26 26.1 26.1 26.2 26.2 26.3 26.3 26.4 26.5 26.5 26.5 26.5 26.6 26.6 26.7 26.7 26.7 26.8 26.8 26.9 26.9 26.9 26.9 27 27 27.1 27.3 27.5 27.5 27.6 27.9 28 28.3 28.3 28.6 29 31
Stem-and-leaf plot
In the below software’s stem-and-leaf plot, the decimal point is at the | Displays vary slightly across statistical software
23 | 23356789 24 | 01233345666677788999 25 | 000145566677777899 26 | 000001122334555566777889999 27 | 00135569 28 | 0336 29 | 0 30 | 31 | 0
Determine the original data set:(The decimal point is 1 digit(s) to the right of the |)
0| 234 0 | 5889 1 | 000134444 1 | 578 2 | 00(A) 0.2, 0.3, 0.4, 0.5, 0.8, 0.8, 0.9, 1, 1, 1, 1.1, 1.3, 1.4, 1.4, 1.4, 1.4, 1.5, 1.7,
1.8, 2, 2 (B) 2, 3, 4, 5, 8, 8, 9, 10, 10, 10, 11, 13, 14, 14, 14, 14, 15, 17, 18, 20, 20(C) 234, 5889, 1000, 1001, 1003, 1004, 1004, 1004, 1004, 1004, 1587, 200(D) 0.234, 0.5889, 1.000134444, 1.578, 2.00
Create a stem-and-leaf plot for values:24,25,26,29,29,30,31,31,35,36,36
2 | 4 2 | 5699 3 | 011 3 | 566
2 | 45699 3 | 011566
Dot Plot
Sparrow weights (grams)
Co
un
t
0
5
10
15
20
25
24 26 28 30
Bad graphs…
