 8.R8.1: Conditions Martin says that the relative importance of the three co...
 8.R8.2: Its critical Find the appropriate critical value for constructing a...
 8.R8.3: Batteries A company that produces AA batteries tests the lifetime o...
 8.R8.4: We love football! A recent Gallup Poll conducted telephone intervie...
 8.R8.5: Smart kids A school counselor wants to know how smart the students ...
 8.R8.6: Do you go to church? The Gallup Poll plans to ask a random sample o...
 8.R8.7: Running red lights A random digit dialing telephone survey of 880 d...
 8.R8.8: Engine parts Here are measurements (in millimeters) of a critical d...
 8.R8.9: Good wood? A lab supply company sells pieces of Douglas fir 4 inche...
Solutions for Chapter 8: The Practice of Statistics 4th Edition
Full solutions for The Practice of Statistics  4th Edition
ISBN: 9781429245593
Solutions for Chapter 8
Get Full SolutionsThis expansive textbook survival guide covers the following chapters and their solutions. This textbook survival guide was created for the textbook: The Practice of Statistics, edition: 4. Since 9 problems in chapter 8 have been answered, more than 4323 students have viewed full stepbystep solutions from this chapter. Chapter 8 includes 9 full stepbystep solutions. The Practice of Statistics was written by and is associated to the ISBN: 9781429245593.

Additivity property of x 2
If two independent random variables X1 and X2 are distributed as chisquare with v1 and v2 degrees of freedom, respectively, Y = + X X 1 2 is a chisquare random variable with u = + v v 1 2 degrees of freedom. This generalizes to any number of independent chisquare random variables.

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

Axioms of probability
A set of rules that probabilities deined on a sample space must follow. See Probability

Bayes’ theorem
An equation for a conditional probability such as PA B (  ) in terms of the reverse conditional probability PB A (  ).

Center line
A horizontal line on a control chart at the value that estimates the mean of the statistic plotted on the chart. See Control chart.

Central limit theorem
The simplest form of the central limit theorem states that the sum of n independently distributed random variables will tend to be normally distributed as n becomes large. It is a necessary and suficient condition that none of the variances of the individual random variables are large in comparison to their sum. There are more general forms of the central theorem that allow ininite variances and correlated random variables, and there is a multivariate version of the theorem.

Completely randomized design (or experiment)
A type of experimental design in which the treatments or design factors are assigned to the experimental units in a random manner. In designed experiments, a completely randomized design results from running all of the treatment combinations in random order.

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

Conditional probability density function
The probability density function of the conditional probability distribution of a continuous random variable.

Conditional probability distribution
The distribution of a random variable given that the random experiment produces an outcome in an event. The given event might specify values for one or more other random variables

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

Cook’s distance
In regression, Cook’s distance is a measure of the inluence of each individual observation on the estimates of the regression model parameters. It expresses the distance that the vector of model parameter estimates with the ith observation removed lies from the vector of model parameter estimates based on all observations. Large values of Cook’s distance indicate that the observation is inluential.

Correlation
In the most general usage, a measure of the interdependence among data. The concept may include more than two variables. The term is most commonly used in a narrow sense to express the relationship between quantitative variables or ranks.

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.

Decision interval
A parameter in a tabular CUSUM algorithm that is determined from a tradeoff between false alarms and the detection of assignable causes.

Degrees of freedom.
The number of independent comparisons that can be made among the elements of a sample. The term is analogous to the number of degrees of freedom for an object in a dynamic system, which is the number of independent coordinates required to determine the motion of the object.

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

Expected value
The expected value of a random variable X is its longterm average or mean value. In the continuous case, the expected value of X is E X xf x dx ( ) = ?? ( ) ? ? where f ( ) x is the density function of the random variable X.

Fractional factorial experiment
A type of factorial experiment in which not all possible treatment combinations are run. This is usually done to reduce the size of an experiment with several factors.

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 .