Econ 391 Exam

Variation in production caused by a specific event or factor that can usually be identified and eliminated is called_______

assignable variation.

CLM states that for any distribution, as n gets larger, the sampling distribution of the sample mean becomes __________ .

close to a normal

Random variable x with an equally likely chance of assuming any value within a specified range is said to have a ____________.

continuous uniform distribution.

If an unbiased estimator is ______ its standard error must be lower than that of other unbiased estimators.

efficient

The sample size required to approximate the normal distribution depends on _________

how much the population varies from normality

The value of the finite population corrector factor is always

less than one

as sample size increase, the shape of the sampling distribution of p bar becomes ______.

more normal

Sampling Distribution of the sample porportion is approximately normal distributed if ______

np >_ 5 and n(1-P)>_ 5

Nonresponse bias

occurs when those responding to a survey or poll differ systematically from the non-respondents.

We use the finite population corrector to reduce the sampling variation of x bar and ______

p bar.

Expected value of p bar is the proportion of successes in the ________.

population.

Cumulative probabilities?

probability that z is less than or equal to a given z value.

sample statistic is a __________

random variable

statistic = ________ estimate= ________ parameter= __________

random variable particular value of an estimator constant

A manufacturing process is in control if the sample means are

randomly spread out between the control limits

probability distribution of the sample mean is referred to as the _____

sample distribution of x bar.

A bad sample is _________

sample is not representative of the population we are trying to explain.

Simple random sample

sample of n observations which has the same probablitiy of being selected from the population as any other n observations.

The variance of x bar, which is equal to std dev ^2 /n is

smaller than the variance of the individual observation.

Bias refers to _____

tendency of a sample statistic to systematically over or under estimate a population parameter.

A control chart is a plot of calculated statistics of a production process over ______

time.

Expected value of x bar is equal to ______.

u

For an x bar chart, central limits are calcualted as ________ .

u +/- 3 std dev/square root of n.

A continuous random variable has the uniform distribution on the interval (a,b) if its probablity density function is constant for all ____ and between ______ otherwise.

x; a and b and 0.

In order to transform a standard normal value z into its unstardized value x, use the equation.

x=u+z*std dev

we can use the finite population correction factor when n > or equal to _________.

.05n

Probablity that a continuous random variable x assumes a particular value x is ______.

0. P(X=x)=0

Mean and variance of the standard normal distribution are ____ and _____.

0;1

In order to transform a value x into it's standardized value z, use the equation.

z= x-u/std dev