Solutions for Chapter 6: Descriptive Statistics

A formula used to determine the probability of the union of two (or more) events from the probabilities of the events and their intersection(s).

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

Unbiased estimator.

The joint probability distribution of two random variables.

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

A chart used to organize the various potential causes of a problem. Also called a ishbone diagram.

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

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

A continuous random variable with range of a inite interval and a constant probability density function.

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 .

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.

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

Another name for a probability density function

An experiment in which the tests are planned in advance and the plans usually incorporate statistical models. See Experiment

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.

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

The numerical value of a point estimator.

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

A method of variable selection in regression, where variables are inserted one at a time into the model until no other variables that contribute signiicantly to the model can be found.

A random variable that generalizes an Erlang random variable to noninteger values of the parameter r