AP Statistics
Chapter 4 Outline
ASSIGNMENTS:
10/2 Read 4.1
4.1 Page 226 #1-9 odd
10/5 Read 4.2
4.1 # 17, 19, 21, 25, 27, 28, 31
Name:______________________________
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10/7 4.2 # 63, 67, 69, 73, 75, 77, 81
10/12 4.3 #102-108
10/14 Review
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Population and Sample
Bad Sampling (2 kinds)
SRS
Cluster Sampling and Stratified
Sampling
Sample Surveys: What can go
wrong (4 things)
Observational Study versus
Experiment
Lurking Variable
Confounding
 Treatment, Experimental
units & Subjects
 Completely Randomized
Design
 Principles of Experimental
Design
 Double Blind
 Statistically Significant
 Block Design and
Randomized Block Design
10/16 Chapter 4 Test
4.1 Sampling and Surveys
The population in a statistical study is the entire group of individuals about which we want information.
A sample is the part of the population from which we actually collect information. We use information
from a sample to draw conclusions about the entire population.
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Is a sample does not represent the population well, it is ____________
Bad Sampling:
Convenience Sample:
Voluntary Response Sample:
Random Sampling
 _____________________________ (SRS) of size n consists of n individuals from the population
chosen in such a way that every set of n individuals has an _____________________ to be the
sample actually selected.
Other Types of Random Sampling
Stratified Random Sample:
Cluster Sample:
Sample Surveys: What can go wrong?
Undercoverage
Nonresponse Bias
Response Bias
Wording of Question
4.2 Experiments
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An observational study observes individuals and measures variables of interest but does not
attempt to influence the responses.
An experiment deliberately imposes some treatment on individuals to measure their responses.
Vocabulary:
Lurking Variable:
Example of Lurking Variable:
Confounding:
Example of Confounding:
Treatment:
Example of a Treatment:
Experimental units are the smallest collection of individuals to which treatments are applied.
Subjects: When the units are human beings.
Random assignment in an experiment means that experimental units are assigned to treatments at
random, that is, using some sort of chance process.
Completely randomized design:
Control Group:
3 Principals of Experimental Design:
Control
Random Assignment:
Replication:
Placebo Affect: “dummy pill” or inactive treatment that is indistinguishable from the real treatment.
Double Blind: neither the subjects nor those who interact with them and measure the response variable
know which treatment a subject received.
Example:
Block is a group of experimental units that are known before the experiment to be similar in some way
that is expected to affect the response to the treatments.
Randomized block design, the random assignment of experimental units to treatments is carried out
separately within each block.
Example:
Matched Pairs Design: randomized blocked experiment in which each block consists of a matching pair of
similar experimental units.
Example:
Statistically Significant: When an observed effect is so large that is would rarely occur by chance