CH 7 ORMS 3310

As the sample size increases, what happens to the standard deviation of XX?

It gets smaller.

Which one of the following is true about stratified and cluster sampling?

Stratified sampling provides greater precision.

True or false: Most statistical methods presume simple random samples.

True

If X is normally-distributed, we can transform XX into the standard normal random variable as

Z = X−μσ/√n

In statistical quality control, a tool used to monitor the behavior of a production process over time is called

a control chart.

A sample is

a subset of the population.

In general, the two approaches that are used for statistical quality control are

acceptance sampling and the detection approach.

If the population from which the sample is drawn is normally distributed, then the sampling distribution of the sample mean is

always normally distributed.

In general, the control limits of a control chart are set at ______ standard deviations from the centerline.

3

The general rule for using the finite correction factor is that the sample constitutes at least _____ of the population.

5%

A variation in production caused by a specific event or factor that can usually be identified and eliminated is called

assignable variation.

Which of the following statements is MOST accurate? X

A parameter is a constant although its value may be unknown.

Which of the following statements is MOST accurate?

A statistic is a random variable whose value depends on the chosen random sample.

is caused by a number of randomly occurring events that are part of the production process.

Chance variation

We use the finite population correction factor to

reduce the sampling variation of X⎯⎯⎯ and P.

A population consists of all items of interest in a statistical problem, whereas a ______ is a subset of the population

sample

When a voter provides incorrect answers to a survey or poll because they think that others will look unfavorably on their choices, this is referred to as

social

Assignable variation is caused by

specific events that can usually be identified and eliminated.

We use a calculated sample ______ to make inferences about an unknown populatioN

statistic, parameter

In ______, the population is divided up into mutually exclusive and collectively exhaustive groups called strata. The sample consists of randomly-selected elements from each stratum

stratified random sampling

In ______, the population is divided up into strata and then randomly selected observations are taken proportionately from each stratum.

stratified random sampling

Selection bias occurs when

there is a systematic exclusion of certain groups from consideration for the sample.

Cluster sampling works best

when most of the variation in a population is within groups and not between groups.

A particular value of an estimator is called a/an

estimate

The sample size required to approximate the normal distribution depends on

how much the population varies from normality.

A sampling distribution (select all that apply)

is the same as the probability distribution for a statistic. is distribution of a statistic that is calculated from all possible samples of size n from a population.

A firm uses acceptance sampling when

it produces a product and at the end of the process, inspects a portion.

In general, the variability between sample means is ______ the variability between observations

less than

The value of the finite population correction factor is always

less than one.

Control charts were created to

monitor the behavior of a production process.

We can use the finite population correction factor when

n ≥ 0.05N.

Social-desirability bias exists when

opinions that are socially unacceptable are not expressed.

The expected value of PP is the

proportion of successes in the population.

When a firm applies statistical techniques to develop and maintain its ability to produce high-quality goods and services, it is implementing statistical

quality control

A manufacturing production process is in control if the sample means are

randomly spread out between the control limits.

If X is normally distributed with expected value μ and standard deviation σ, then XX is normally distributed with

expected value μ and standard deviation σ/√nn.

The purpose of statistical quality control is to

maintain high-quality goods and services.

If we were to sample repeatedly from a given population, the average value of the sample means will equal

the population mean.

Bias can occur in sampling. Bias refers to

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

Nonresponse bias occurs when

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

If pp is the sample proportion from a sample that is large enough, then we can transform the proportion into its standard normal value as

z=p⎯⎯−pp(1−p)n√

The expected value of X- is equal to ______

μ

When the finite population correction factor is applied to the sample proportion, the resulting standard error for the sample proportion is equal to

√p(1−p)/np(1-p)/n×√(N−n)/(N−1)(N-n)/(N-1).

The standard deviation of PP equals

√p(1−p)n

A university's athletic program is considering changing its mascot. The SGA administers a survey to assess students' opinions by going to the business building. What type of bias is likely?

Selection Bias

Which of the following are true about the standard deviation of the sample mean? Select all that apply.

The less variability there is in the population, the less variability there will be in the sample means. Another name for the standard deviation of the sample mean is the the standard error of the sample mean.

Which of these is a characteristic of a "bad" sample?

The sample is not representative of the population being studied.

If a sample statistic consistently over- or under-estimates a population parameter, then there is

bias

For any population proportion p, the sampling distribution of the sample proportion is approximately normally distributed if

np ≥ 5 and n(1 - p) ≥ 5.

When a sample of n observations that has the same probability of being selected from the population as any other sample of n observations is called a

simple random sample

Stratified sampling is preferred to cluster sampling when the objective is

to increase precision.

True or false: If we had access to data that included the entire population, then the values of the parameters would be known and no statistical inference would be required

true

True or false: A process could be veering out of control if there is a trend within the upper and lower control limits of a control chart.

True

When the finite population correction factor is applied to the sample mean, the resulting standard error for the sample mean is equal to

(σ/√n)σ/n√(N−n)/(N−1)(N-n)/(N-1).

the central limit theorem states that as n gets larger, the sampling distribution of the sample proportion

approaches a normal distribution.

The central limit theorem states that as n gets larger, the sampling distribution of the sample proportion

approaches a normal distribution.

Sample means or sample proportions being monitored by using a control chart should lie

between the upper and lower control limits.

When a sample statistic is used to make inferences about a population parameter, it is referred to as a/an

estimator.

Which of the following is considered an estimate?

x- = 20

The central limit theorem states that, for any distribution, as n gets larger, the sampling distribution of the sample mean becomes

closer to a normal distribution.

Which of the following is an example of a sample statistic?

-x

In any production process, variation in the quality of the end product is inevitable. Chance variation, or common variation, refers to

A number of randomly occurring events that are part of the production process.

involves dividing a population into mutually exclusive and exhaustive groups, and then selecting a random sample from these groups for analysis

Cluster sampling

involves dividing a population into mutually exclusive and exhaustive groups, and then selecting a random sample from these groups for analysis.

Cluster sampling

What is a primary requirement of a "good" sample?

It is representative of the population we are trying to describe.

Which of the following are components of a control chart? Select all that apply.

Lower control limit (LCL) Centerline Upper control limit (UCL)

The branch of statistics that uses sample statistics to estimate a population parameter or test a hypothesis about such a parameter is BEST referred to as

inferential statistics

If the shape of the population from which a simple random sample is drawn is normal, then the shape of the sampling distribution of XX is

normal.