Workshop Statistics: Discovery with Data and Fathom

Topic 8: Graphical Displays of Association

Activity 8-1: Cars' Fuel Efficiency (cont.)

(a) observational units: cars
(b) 2 variables are reported for each car (c)
(d) Yes, the scatterplot reveals a relationship between the car's weight and its fuel efficiency.  So, knowing the car's weight reveals information about its fuel efficiency.  It appears that cars that weigh less get better mileage than cars that weigh more.
(e) Fuel efficiency is negatively associated with weight.
(f) Yes, there are several such examples, e.g. eclipse and cougar.
 

Activity 8-2: Guess the Association

(a) Answers will vary from student to student, but this is a good example:
 
 
strongly
negative
  
mildly
negative
  
virtually
none
  
mildly
positive
  
strongly positive
letter:
D
G
A
H
C
E
I
F
B

(b) Answers will vary from student to student, but this is a good example:
 
pair of variables
direction
strength
length and width of signatures
positive
weak 
SAT score & college GPA 
 positive
strong 
latitude & avg. January temperature of U.S. cities 
negative 
strong 
lifetime & weekly cigarette consumption 
negative 
moderate 
 serving size & calories of fast food sandwiches
positive 
moderate 
 airfare & distance to the destination
positive 
moderate 
birth rates & death rates of U.S. states 
none at all 
none 
foot length & height
positive 
strong 

Activity 8-3: Marriage Ages (cont.)

(a) There is a fairly strong positive association between the husband's age and the wife's age.
(b) 2
(c) 16, above the line
(d) 5, below the line
(e) According to the data collected, the husband tends to be older than the wife in married couples.
 

Activity 8-4: Space Shuttle O-Ring Failures

(a)

(b) There seems to be a slightly negative association between O-ring failures and temperature, with fewer failures at higher temperatures.
(c) It seems very likely that there would be an O-ring failure.
(d)

(e)  This scatterplot does not show any real association.
(f) Considering that all the flights with no failures occured at relatively high temperatures, the flights with zero failures gave a lot of information about how failures were related to temperature.
 

Activity 8-5: Fast Food Sandwiches

(a)

        There is a fairly strong positive association between a sandwich's serving size and its calories.  The number of calories tends to increase with the number of ounces in a serving.

(b)

        Roast beef tends to have more calories than other sandwiches of similar serving sizes but different meats.  Turkey tends to have less calories than other sandwiches of similar serving sizes but different meats.  Ham and chicken seem to vary.
(c)

(d) Answers will vary from student to student.