GLOSSARY 691Conditional mean.The mean of the conditional prob-
ability distribution of a random variable.
Conditional probability.The probability of an event
given that the random experiment produces an outcome
in another event.
Conditional probability density function.The proba-
bility 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 probability mass function.The proba-
bility mass function of the conditional probability
distribution of a discrete random variable.
Conditional variance.The variance of the conditional
probability distribution of a random variable.
Confidence coefficient.The probability 1associ-
ated with a confidence interval expressing the probability
that the stated interval will contain the true parameter
value.
Confidence interval.If it is possible to write a proba-
bility statement of the formwhere Land Uare functions of only the sample data and
is a parameter, then the interval between Land Uis
called a confidence interval (or a 100(1 )% confi-
dence 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.
Confidence level. Another term for the confidence
coefficient.
Confounding.When a factorial experiment is run in
blocks and the blocks are too small to contain a com-
plete replicate of the experiment, one can run a fraction
of the replicate in each block, but this results in losing
information on some effects. These effects are linked
with or confounded with the blocks. In general, when
two factors are varied such that their individual effects
cannot be determined separately, their effects are said to
be confounded.
Consistent estimator.An estimator that converges in
probability to the true value of the estimated parameter
as the sample size increases.P 1 L U 2 1 Contingency table.A tabular arrangement expressing
the assignment of members of a data set according to
two or more categories or classification criteria.
Continuity correction.A correction factor used to im-
prove the approximation to binomial probabilities from
a normal distribution.
Continuous distribution.A probability distribution
for a continuous random variable.
Continuous random variable.A random variable
with an interval (either finite or infinite) of real numbers
for its range.
Continuous uniform random variable.A continuous
random variable with range of a finite interval and a
constant probability density function.
Contour plot.A two-dimensional graphic used for a
bivariate probability density function that displays
curves for which the probability density function is
constant.
Control chart.A graphical display used to monitor a
process. It usually consists of a horizontal center line
corresponding to the in-control value of the parameter
that is being monitored and lower and upper control
limits. The control limits are determined by statistical
criteria and are not arbitrary nor are they related to spec-
ification limits. If sample points fall within the control
limits, the process is said to be in-control, or free from
assignable causes. Points beyond the control limits indi-
cate an out-of-control process; that is, assignable causes
are likely present. This signals the need to find and re-
move the assignable causes.
Control limits.SeeControl chart.
Convolution.A method to derive the probability den-
sity function of the sum of two independent random
variables from an integral (or sum) of probability
density (or mass) functions.
Cook’s distance.In regression, Cook’s distance is a
measure of the influence of each individual observation
on the estimates of the regression model parameters. It
expresses the distance that the vector of model parame-
ter estimates with the ith observation removed lies from
the vector of model parameter estimates based on all ob-
servations. Large values of Cook’s distance indicate that
the observation is influential.
Correction factor.A term used for the quantity
that is subtracted from
to give the corrected sum of squares defined as. The correction factor can also be
written as nx^2.
(^11) n 2 gni 11 xix 22
(^11) n 21 gni 1 xi 22 gni 1 xi^2
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