 12.1: At one time, a method called gastric freezing was used to treat peo...
 12.2: Recall the experiment about gastric freezing, an old method for tre...
 12.3: MS and vitamin D Multiple sclerosis (MS) is an autoimmune disease t...
 12.4: Super Bowl commercials When spending large amounts to purchase adve...
 12.5: Maggot therapy? People generally dont think health when they hear t...
 12.6: Honesty Coffee stations in offices often just ask users to leave mo...
 12.7: Superglue 130 patients with eligible lacerations randomly assigned ...
 12.8: Truancy A group of researchers analyzed three observational studies...
 12.9: Hypertension In a test of roughly 200 older men and women, those wi...
 12.10: Tossing and turning Is diet or exercise effective in combating inso...
 12.11: Alcohol and estrogen After menopause, some women take supplemental ...
 12.12: Dioxin Researchers have linked an increase in the incidence of brea...
 12.13: Boys and girls In 2002 the journal Science reported that a study of...
 12.14: Herbal remedy Scientists at a major pharmaceutical firm investigate...
 12.15: Depression The May 4, 2000, issue of Science News reported that, co...
 12.16: Vitamin C doping Some people who race greyhounds give the dogs larg...
 12.17: Torn ACL Having at least one 15minute warmup session per week res...
 12.18: Losing sleep An article entitled TV Before Bed May Rob Teens of Sle...
 12.19: Migraines Some people claim they can get relief from migraine heada...
 12.20: Lowcal dog food A dog food company wants to compare a new lower ca...
 12.21: Omega3 An experiment that showed that high doses of omega3 fats m...
 12.22: Insomnia Exercise 10 describes an experiment showing that exercise ...
 12.23: Omega3 revisited Exercises 21 describes an experiment investigatin...
 12.24: Insomnia again Exercises 10 and 22 describe an experiment investiga...
 12.25: Omega3, finis Exercises 21 and 23 describe an experiment investiga...
 12.26: Insomnia, at last Exercises 10, 22, and 24 describe an experiment i...
 12.27: Tomatoes Describe a strategy to randomly split the 24 tomato plants...
 12.28: Tomatoes II The chapter also described a completely randomized two...
 12.29: Shoes A runningshoe manufacturer wants to test the effect of its n...
 12.30: Swimsuits A swimsuit manufacturer wants to test the speed of its ne...
 12.31: Hamstrings Athletes who had suffered hamstring injuries were random...
 12.32: Diet and blood pressure An experiment that showed that subjects fed...
 12.33: Mozart Will listening to a Mozart piano sonata make you smarter? In...
 12.34: Full moon Its a common belief that people behave strangely when the...
 12.35: Wine A 2001 Danish study published in the Archives of Internal Medi...
 12.36: Swimming Recently, a group of adults who swim regularly for exercis...
 12.37: Dowsing Before drilling for water, many rural homeowners hire a dow...
 12.38: Healing A medical researcher suspects that giving postsurgical pati...
 12.39: Reading Some schools teach reading using phonics (the sounds made b...
 12.40: Gas mileage Do cars get better gas mileage with premium instead of ...
 12.41: Weekend deaths A study published in the New England Journal of Medi...
 12.42: Shingles A research doctor has discovered a new ointment that she b...
 12.43: Beetles Hoping to learn how to control crop damage by a certain spe...
 12.44: SAT Prep Can special study courses actually help raise SAT scores? ...
 12.45: Safety switch An industrial machine requires an emergency shutoff s...
 12.46: Washing clothes A consumer group wants to test the effectiveness of...
 12.47: Skydiving, anyone? A humor piece published in the British Medical J...
Solutions for Chapter 12: Experiments and Observational Studies
Full solutions for Stats Modeling the World  4th Edition
ISBN: 9780321854018
Solutions for Chapter 12: Experiments and Observational Studies
Get Full SolutionsThis textbook survival guide was created for the textbook: Stats Modeling the World, edition: 4. This expansive textbook survival guide covers the following chapters and their solutions. Since 47 problems in chapter 12: Experiments and Observational Studies have been answered, more than 19429 students have viewed full stepbystep solutions from this chapter. Chapter 12: Experiments and Observational Studies includes 47 full stepbystep solutions. Stats Modeling the World was written by and is associated to the ISBN: 9780321854018.

Analytic study
A study in which a sample from a population is used to make inference to a future population. Stability needs to be assumed. See Enumerative study

Assignable cause
The portion of the variability in a set of observations that can be traced to speciic causes, such as operators, materials, or equipment. Also called a special cause.

Causal variable
When y fx = ( ) and y is considered to be caused by x, x is sometimes called a causal variable

Chisquare (or chisquared) random variable
A continuous random variable that results from the sum of squares of independent standard normal random variables. It is a special case of a gamma random variable.

Coeficient of determination
See R 2 .

Correlation matrix
A square matrix that contains the correlations among a set of random variables, say, XX X 1 2 k , ,…, . The main diagonal elements of the matrix are unity and the offdiagonal elements rij are the correlations between Xi and Xj .

Counting techniques
Formulas used to determine the number of elements in sample spaces and events.

Covariance matrix
A square matrix that contains the variances and covariances among a set of random variables, say, X1 , X X 2 k , , … . The main diagonal elements of the matrix are the variances of the random variables and the offdiagonal elements are the covariances between Xi and Xj . Also called the variancecovariance matrix. When the random variables are standardized to have unit variances, the covariance matrix becomes the correlation matrix.

Defectsperunit control chart
See U chart

Dependent variable
The response variable in regression or a designed experiment.

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

Error of estimation
The difference between an estimated value and the true value.

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.

Experiment
A series of tests in which changes are made to the system under study

Extra sum of squares method
A method used in regression analysis to conduct a hypothesis test for the additional contribution of one or more variables to a model.

False alarm
A signal from a control chart when no assignable causes are present

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

Generator
Effects in a fractional factorial experiment that are used to construct the experimental tests used in the experiment. The generators also deine the aliases.

Geometric mean.
The geometric mean of a set of n positive data values is the nth root of the product of the data values; that is, g x i n i n = ( ) = / w 1 1 .