jan. 23 statistic for the day: average number of times an american opens the refrigerator each day:...
TRANSCRIPT
Jan. 23 Statistic for the Day:Average Number of Times an
American Opens the Refrigerator Each Day: 22
Assignment: Having read Chapter 9, Assignment: Having read Chapter 9, go back and study it closely.go back and study it closely.
Exercises p153-155: 1, 2, 4, 5, 9Exercises p153-155: 1, 2, 4, 5, 9
These slides were created by Tom Hettmansperger and in some cases modified by David Hunter
Source: Harper’s Magazine
Recall
Research Question or HypothesisResearch Question or Hypothesis QuantificationQuantification Collect dataCollect data Analyze dataAnalyze data Conclusions and/or actionConclusions and/or action
As first step in extracting information from data use graphics or pictures:
BoxplotBoxplot Stem and leafStem and leaf
Median and quartilesMedian and quartiles Histogram or normal curveHistogram or normal curve
Mean and standard deviationMean and standard deviation
Boxplot
stat100 PSUfootball
100
200
300
Weight
Overlapping Histograms
Stat100
PSU football
100 200 300
0
10
20
30
C68
Fre
que
ncy
Histogram with Normal Curve
100 150 200
0
10
20
Fre
quen
cy
Stat 100 Women: Weight
Scatter Plot for two measurements: RELATIONSHIP
100 200 300
100
200
300
weight
ide
al w
t
Stat 100 F01
US Pop and Violent CrimeTable 9.2 p155 text
YearYear 19821982 19831983 19851985 19861986 19871987 19881988 19891989 19901990 19911991
US PopUS Pop 231231 234234 239239 241241 243243 246246 248248 249249 252252
No. No. crimescrimes
1.321.32 1.261.26 1.331.33 1.491.49 1.481.48 1.571.57 1.651.65 1.821.82 1.911.91
In millions
250240230
8
7
6
5
4
3
2
1
0
pop
no./
10
00
If we want to suggest a much more dramatic increase:
250240230
7.5
6.5
5.5
pop
no./
10
00
Enrolment in higher educationAs percent of population
Moral of the story:
Whenever you meet a graph that is very far from square, it is likely to producean impression different from what you would have obtained from the data themselves.
Almost any graph in which the vertical scale does not start with zero is deceptive.
Another moral:
This Is a Good Bar GraphEarned Degrees 1976 in
thousands
0100200300400500600
MenWomen
BAD
• The problem with the pens is that it is the heights that should be compared.
• But instead, we end up comparing the areas.
• The areas do not make the correct comparison.
GOOD But with an error
•The letters are good because each letter represents an amount.
• However, one should use the correct number of letters
Bogus vertical scale. Hard to say what the graph should look like.
Portion of income taken by the government. Top: spending equal to the income in western states. Bottom: more densely populated east.
Some people think it means that rhinos have gotten smaller!