 12.1: Roper. Through their Roper Reports Worldwide, GfKRoper conducts a g...
 12.2: Student Center Survey. For their class project, agroup of Statistic...
 12.3: Emoticons. The Web site www.gamefaqs.com asked,as their question of...
 12.4: Drug tests. Major League Baseball tests players to seewhether they ...
 12.5: Gallup. At its Web site (www.gallup.com) the GallupPoll publishes r...
 12.6: Gallup World. At its Web site (www.gallupworldpoll.com) the Gallup ...
 12.7: Consumers Union asked all subscribers whether they hadused alternat...
 12.8: A question posted on the Lycos Web site on 18 June 2000asked visito...
 12.9: Researchers waited outside a bar they had randomlyselected from a l...
 12.10: Hoping to learn what issues may resonate with voters inthe coming e...
 12.11: The Environmental Protection Agency took soil samplesat 16 location...
 12.12: State police set up a roadblock to estimate the percentageof cars w...
 12.13: A company packaging snack foods maintains quality control by rando...
 12.14: Dairy inspectors visit farms unannounced and take samples of the m...
 12.15: Mistaken poll. A local TV station conducted aPulsePoll about the up...
 12.16: Another mistaken poll. Prior to the mayoral electiondiscussed in Ex...
 12.17: Parent opinion, part 1. In a large city school systemwith 20 elemen...
 12.18: Parent opinion, part 2. Lets revisit the school systemdescribed in ...
 12.19: Churches. For your political science class, youd like totake a surv...
 12.20: Playground. Some people have been complaining thatthe childrens pla...
 12.21: Roller coasters. An amusement park has opened anew roller coaster. ...
 12.22: Playground, act two. The survey described in Exercise 20 asked,Man...
 12.23: Wording the survey. Two members of the PTA committee in Exercises ...
 12.24: Banning ephedra. An online poll at a Web site asked:A nationwide ba...
 12.25: Survey questions. Examine each of the followingquestions for possib...
 12.26: More survey questions. Examine each of the following questions for...
 12.27: Phone surveys. Anytime we conduct a survey, wemust take care to avo...
 12.28: Cell phone survey. What about drawing a randomsample only from cell...
 12.29: Arm length. How long is your arm compared withyour hand size? Put y...
 12.30: Fuel economy. Occasionally, when I fill my car with gas,I figure ou...
 12.31: Accounting. Between quarterly audits, a companylikes to check on it...
 12.32: Happy workers? A manufacturing company employs 14project managers, ...
 12.33: Quality control. Sammys Salsa, a small local company, produces 20 ...
 12.34: A fish story. Concerned about reports of discoloredscales on fish c...
 12.35: Sampling methods. Consider each of these situations.Do you think th...
 12.36: More sampling methods. Consider each of these situations. Do you t...
Solutions for Chapter 12: Sample Surveys
Full solutions for Stats: Modeling The World  3rd Edition
ISBN: 9780131359581
Solutions for Chapter 12: Sample Surveys
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Alias
In a fractional factorial experiment when certain factor effects cannot be estimated uniquely, they are said to be aliased.

Binomial random variable
A discrete random variable that equals the number of successes in a ixed number of Bernoulli trials.

Categorical data
Data consisting of counts or observations that can be classiied into categories. The categories may be descriptive.

Components of variance
The individual components of the total variance that are attributable to speciic sources. This usually refers to the individual variance components arising from a random or mixed model analysis of variance.

Conditional variance.
The variance of the conditional probability distribution of a random variable.

Conidence interval
If it is possible to write a probability statement of the form PL U ( ) ? ? ? ? = ?1 where L and U are functions of only the sample data and ? is a parameter, then the interval between L and U is called a conidence interval (or a 100 1( )% ? ? conidence interval). The interpretation is that a statement that the parameter ? lies in this interval will be true 100 1( )% ? ? of the times that such a statement is made

Continuous distribution
A probability distribution for a continuous random variable.

Covariance
A measure of association between two random variables obtained as the expected value of the product of the two random variables around their means; that is, Cov(X Y, ) [( )( )] =? ? E X Y ? ? X Y .

Critical value(s)
The value of a statistic corresponding to a stated signiicance level as determined from the sampling distribution. For example, if PZ z PZ ( )( .) . ? =? = 0 025 . 1 96 0 025, then z0 025 . = 1 9. 6 is the critical value of z at the 0.025 level of signiicance. Crossed factors. Another name for factors that are arranged in a factorial experiment.

Defect
Used in statistical quality control, a defect is a particular type of nonconformance to speciications or requirements. Sometimes defects are classiied into types, such as appearance defects and functional defects.

Deming
W. Edwards Deming (1900–1993) was a leader in the use of statistical quality control.

Deming’s 14 points.
A management philosophy promoted by W. Edwards Deming that emphasizes the importance of change and quality

Error mean square
The error sum of squares divided by its number of degrees of freedom.

Error sum of squares
In analysis of variance, this is the portion of total variability that is due to the random component in the data. It is usually based on replication of observations at certain treatment combinations in the experiment. It is sometimes called the residual sum of squares, although this is really a better term to use only when the sum of squares is based on the remnants of a modelitting process and not on replication.

Error variance
The variance of an error term or component in a model.

Factorial experiment
A type of experimental design in which every level of one factor is tested in combination with every level of another factor. In general, in a factorial experiment, all possible combinations of factor levels are tested.

Firstorder model
A model that contains only irstorder terms. For example, the irstorder response surface model in two variables is y xx = + ?? ? ? 0 11 2 2 + + . A irstorder model is also called a main effects model

Gamma function
A function used in the probability density function of a gamma random variable that can be considered to extend factorials

Geometric random variable
A discrete random variable that is the number of Bernoulli trials until a success occurs.

Hat matrix.
In multiple regression, the matrix H XXX X = ( ) ? ? 1 . This a projection matrix that maps the vector of observed response values into a vector of itted values by yˆ = = X X X X y Hy ( ) ? ? ?1 .