 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 10299 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.

Arithmetic mean
The arithmetic mean of a set of numbers x1 , x2 ,…, xn is their sum divided by the number of observations, or ( / )1 1 n xi t n ? = . The arithmetic mean is usually denoted by x , and is often called the average

Attribute
A qualitative characteristic of an item or unit, usually arising in quality control. For example, classifying production units as defective or nondefective results in attributes data.

Attribute control chart
Any control chart for a discrete random variable. See Variables control chart.

Backward elimination
A method of variable selection in regression that begins with all of the candidate regressor variables in the model and eliminates the insigniicant regressors one at a time until only signiicant regressors remain

Bayes’ estimator
An estimator for a parameter obtained from a Bayesian method that uses a prior distribution for the parameter along with the conditional distribution of the data given the parameter to obtain the posterior distribution of the parameter. The estimator is obtained from the posterior distribution.

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

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.

Convolution
A method to derive the probability density function of the sum of two independent random variables from an integral (or sum) of probability density (or mass) functions.

Correction factor
A term used for the quantity ( / )( ) 1 1 2 n xi i n ? = that is subtracted from xi i n 2 ? =1 to give the corrected sum of squares deined as (/ ) ( ) 1 1 2 n xx i x i n ? = i ? . The correction factor can also be written as nx 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 .

Cumulative normal distribution function
The cumulative distribution of the standard normal distribution, often denoted as ?( ) x and tabulated in Appendix Table II.

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

Discrete uniform random variable
A discrete random variable with a inite range and constant probability mass function.

Eficiency
A concept in parameter estimation that uses the variances of different estimators; essentially, an estimator is more eficient than another estimator if it has smaller variance. When estimators are biased, the concept requires modiication.

Erlang random variable
A continuous random variable that is the sum of a ixed number of independent, exponential random variables.

Error propagation
An analysis of how the variance of the random variable that represents that output of a system depends on the variances of the inputs. A formula exists when the output is a linear function of the inputs and the formula is simpliied if the inputs are assumed to be independent.

Estimator (or point estimator)
A procedure for producing an estimate of a parameter of interest. An estimator is usually a function of only sample data values, and when these data values are available, it results in an estimate of the parameter of interest.

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.

Finite population correction factor
A term in the formula for the variance of a hypergeometric random variable.

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