Ch. 1
What is the five-number summary?
What is the five-number summary?
Minimum, Q1, Median, Q3, Maximum
pg. 198 #71
a)
When we take a census, we attempt to collect data from...
When we take a census, we attempt to collect data from...
every individual in the population
If knowing the value of one variable helps predict the value of another variable, we say those variables have....
If knowing the value of one variable helps predict the value of another variable, we say those variables have....an association
pg. 202 #3.3(b)
residual = 65,000 - 76,832 = -11,832
The teacher has driven 11,832 fewer miles than predicted based on the age of the car
Explain the difference between the types of inference that can usually be made from an observational study and an experiment.
Explain the difference between the types of inference that can usually be made from an observational study and an experiment.
Experiment: Inference can be made about a population (random selection) and about cause and effect (random assignment of treatments).
Obs. Study: Inference can only be made about a population
pg. 21 #15 (a)
The given percentages are for separate age groups, %'s given are not part of the same "whole"
A standardized score, also known as a ________, can be found by: (give the formula)
A standardized score, also known as a z-score, can be found by:
z = (x - mean) / standard deviation
pg. 202 #R3.3 (a)
y-hat = 3704 + 12,188x
pg. 280 #T4.7
d) a stratified sample from the cities and towns in the market area
pg. 43 #49 (a) and (b)
a) Students probably rounded their answers (some probably also exaggerated)
b) Yes; center for women (175 mins) is greater than for men (120 mins)
What are 5 ways of describing a distribution of quantitative data? Give an example for each.
What are 5 ways of describing a distribution of quantitative data? Give an example for each.
Shape (right/left-skew, describe peaks/gaps)
Outliers (Q1-1.5*IQR or Q3-1.5*IQR)
Center (mean/median)
Variability (SD/variance)
What do r and r2 represent?
What do they mean?
r = correlation coefficient = strength and direction of a relationship between two variables
r2 = coefficient of determination = measures how well a model's independent (explanatory) variable explains the variation in its dependent (response) variable
pg. 279 #R4.7 (a)
Experimental Units: potatoes
Explanatory: storage method and time from slicing until cooking
Response: ratings of color and flavor
Treatments: 1) fresh/immediately, 2) fresh/after an hour, 3) room temp/immediately, 4) room temp/after an hour
Explain how adding/subtracting/multiplying/dividing each observation by a constant impacts:
-center
-location
-variability
-shape
for +/- constant A:
Center/Location: +/- A, Shape/Variability: No Change
for * by A:
Center/Location/Variability: *A, Shape: No Change
What's the formula for slope in the context of a LSRL?
b = r*(sy/sx)
pg. 282 #T4.14 (b) and (c)
b) if subjects all get caffeine the second time, researchers won't know if increase is due to caffeine or practice with the task
c) yes (...)