Deck 6: Statistical Methods in Quality Management

Question 1

As the sample size increases,the standard error of the mean increases,all else being held constant.

Answer 1

False

Question 2

The Histogram tool provides the basic statistical measures of location,dispersion,and shape.

Answer 2

False

Question 3

The variance is the simplest measure of dispersion and is computed as the difference between the maximum value and the minimum value in the data set.

Answer 3

False

Question 4

The Data Validation Toolpak in Microsoft Excel for Windows provides many procedures for conducting statistical analyses.

Question 5

The number of defects observed in a sample is an example of a continuous random variable.

Question 6

The Poisson distribution is closely related to the binomial distribution.

Question 7

Often,the positively skewed data can be transformed to a normal distribution by using a mathematical transformation such as taking logarithms.

Question 8

The sum of the probabilities over all possible outcomes must be between 0 and 1.

Question 9

Distributions with values of coefficient of kurtosis (CK) greater than 3 are more flat with a wide degree of dispersion.

Question 10

The median is the observation that occurs most frequently.

Question 11

A frequency distribution is a table that shows the number of observations in each of several nonoverlapping groups.

Question 12

A random variable is a theoretical description of the outcome of an experiment.

Question 13

Products are boxed in groups of 25.Drawing a sample of boxes and inspecting all units in the boxes selected is an example of systematic sampling.

Question 14

Two events are independent if they have no outcomes in common.

Question 15

The collection of all possible outcomes of an experiment is called an event.

Question 16

One of the major disadvantages of the Histogram tool is that the results are not dynamically linked to the data.

Question 17

The probability density function for the normal distribution is,

.

Question 18

Statistics is a science concerned with the collection,organization,analysis,interpretation,and presentation of data.

Question 19

A confidence interval is a point estimate of a population parameter.

Question 20

Probability is the likelihood that an outcome occurs.

Question 21

Which of the following is NOT a type of sampling scheme?

A)Stratified sampling
B)Biased sampling
C)Cluster sampling
D)Judgment sampling

Question 22

Partitioning a population into hierarchical groups or levels,and selecting a sample from each group is known as:

A)simple random sampling.
B)stratified sampling.
C)systematic sampling.
D)cluster sampling.

Question 23

Statistical methods help managers make sense of data and gain insight about the:

A)ability of using statistics and quality tools in daily work.
B)nature of variation in all processes.
C)nature of variation in the processes they manage.
D)technology used for data analysis and visualization.

Question 24

The conditional probability of an event A given that event B is known is given by:

A).
B).
C).
D)

Question 25

A _____ is a function that assigns a numerical value to every possible outcome in a sample space.

A)probability distribution
B)population parameter
C)sample statistic
D)random variable

Question 26

A _____ can take on any real value over a specified interval of real numbers.

A)sample space
B)continuous random variable
C)discrete random variable
D)probability distribution

Question 27

Correlation is a measure of a linear or a non-linear relationship between two variables.

Question 28

Which of the following requires the opinion of an expert to determine the location and characteristics of a definable sample group?

A)Judgment sample
B)Simple random sample
C)Systematic sample
D)Stratified sample

Question 29

The component of statistical methodology that includes the collection,organization,and summarization of data is called:

A)descriptive statistics.
B)probability distribution.
C)statistical inference.
D)predictive statistics.

Question 30

The collection of all possible outcomes of an experiment is called the _____.

A)event
B)population
C)sample space
D)random variable

Question 31

All else being equal,as the confidence level increases,the confidence interval becomes larger
to provide higher levels of assurance that the interval contains the true population parameter.

Question 32

_____ is the process of drawing conclusions about unknown characteristics of a population from which data are taken.

A)Descriptive statistics
B)Regression analysis
C)Statistical inference
D)Correlation analysis

Question 33

A perfume bottle is designed to have a capacity of 15 ounces.There is variation in the bottle manufacturing process.Based on historical data,let's suppose that the bottle capacity can be reasonably modeled by a normal distribution with a mean of 15 ounces and a standard deviation of 0.2 ounces.What proportion of these bottles will have a capacity between 14.7 and 15.1 ounces?

A)0.3830
B)0.6247
C)0.8664
D)0.9876

Question 34

When interactions are present in an experiment,main effects have little meaning.

Question 35

The _____ distribution models the time between randomly occurring events.

A)normal
B)Poisson
C)exponential
D)binomial

Question 36

The square of the correlation coefficient is called the coefficient of determination.

Question 37

In general,an experiment with m factors at k levels would have km combinations.

Question 38

The sampling method where every item in the population has an equal probability of being selected is called:

A)simple random sampling.
B)cluster sampling.
C)systematic sampling.
D)judgment sampling.

Question 39

In hypothesis testing,the null hypothesis,H₀,is assumed to be false in the absence of contradictory data.

Question 40

If a normal random variable has a mean
= _____ and a standard deviation
= _____,it is called a standard normal distribution.

A)1;0
B)1;1
C)0;0
D)0;1

Question 41

Based on historical data,the diameter of a ball bearing is normally distributed with a mean of 0.527 cm and a standard deviation of 0.008 cm.Suppose that a sample of 18 ball bearings are randomly selected from a very large lot.Determine the probability that the average diameter of a sampled ball bearing is greater than 0.530 cm.

A)0.2324
B)0.4938
C)0.5062
D)0.0559

Question 42

The approximation to a normal distribution can be assumed for sample sizes of _____.

A)15
B)20
C)25
D)30 or more

Question 43

Group width =

A)(UL - LL)/Number of Groups.
B)Number of Groups/(UL - LL).
C)(UL + LL)/Number of Groups.
D)(UL - LL)(Number of Groups).

Question 44

A manager at a local manufacturing company has been monitoring the output of one of the machines used to manufacture chromium shells.Past data indicate that if the machine is functioning properly,the length of the shells produced by this machine can be modeled as being normally distributed with a mean of 118 centimeters and a standard deviation of 6.3 centimeters.Suppose 10 shells produced by this machine are randomly selected.What is the probability that the average length of these 10 shells will be between 116 and 120 centimeters when the machine is operating "properly?"

A)0.2709
B)0.2943
C)0.9656
D)0.6826

Question 45

A typical group is selected from the population,and a random sample is taken from within the group.This is an example of _____ sampling.

A)simple random
B)stratified
C)cluster
D)judgment

Question 46

A sample of size 16 is randomly selected from a population of size 90.Determine the standard error of the mean if the population standard deviation equals 20.

A)2.11
B)4.16
C)4.56
D)5.00

Question 47

Given here are a set of sample data: 12.0,18.3,29.6,14.3,and 27.8.The sample standard deviation for this data is equal to _____.

A)62.895
B)7.931
C)7.093
D)50.316

Question 48

Which of the following is NOT a tool for descriptive statistics?

A)Frequency distribution
B)Regression analysis
C)Proportion
D)Histogram

Question 49

If random samples are not used,_____ may be introduced.

A)quality control
B)bias
C)testing
D)probability

Question 50

A travel article reasearcher randomly sampled 250 adult residents of Illinois and asked each resident if he/she planned to vacation outside of Illinois this coming summer.Fifty-six of these adults responded that they plan to vacation outside of Illinois.What is the 95% confidence interval for the population proportion of adult residents of Illinois who plan to vacation outside of Illinois this coming summer?

A)(0.178,0.318)
B)(0.246,0.250)
C)(0.172,0.276)
D)(0.142,0.354)

Question 51

Any sampling procedure can result in two types of errors: _____ error and _____ error.

A)standard; variable
B)simple; conditional
C)random; measurement
D)sampling; systematic

Question 52

Calculating the average value of 5 sample measurements of a door width is an example of:

A)descriptive statistics.
B)hypothesis testing.
C)regression analysis.
D)design of experiments.

Question 53

Which of the following constitutes an approach to reducing sampling error?

A)Providing statistical training to workers at all organizational levels
B)Using user-friendly software for data analysis and visualization
C)Taking a larger sample from the population
D)Planning the sampling study carefully

Question 54

_____ involve(s) drawing inferences about two contrasting propositions relating to the value of a population parameter,one of which is assumed to be true in the absence of contradictory data.

A)Probability distributions
B)Hypothesis testing
C)Descriptive statistics
D)Predictive statistics

Question 55

A testing engineer in a light bulb factory is planning a study to estimate the average life of a large shipment of light bulbs.The engineer wants to estimate the average life within plus or minus 16 hours with 95 percent confidence.Assuming a process standard deviation of 90 hours,determine the sample size for this study.

A)7
B)43
C)58
D)122

Question 56

Any sampling procedure can result in _____ types of errors.

A)two
B)three
C)four
D)five

Question 57

Everything else remaining constant,when the sample size increases:

A)the variance decreases.
B)the variance increases.
C)the variance is unaffected.
D)the variance could increase or decrease.

Question 58

A _____ is a subset of objects taken from the _____.

A)population; sample
B)cluster; strata
C)sample; population
D)sample space; experiment

Question 59

A government report gives a 99% confidence interval for the proportion of welfare recipients who have been receiving welfare benefits for more than 5 years to be 21% $\pm$ 4.5%.Which of the following intervals could not be a 95% confidence interval for the proportion of welfare recipients who have been receiving welfare benefits for more than 5 years?

A)21% $\pm$ 4.2%
B)21% $\pm$ 3.76%
C)21% $\pm$ 3.9%
D)21% $\pm$ 4.8%

Question 60

The _____ measures the degree of asymmetry of observations around the mean.

A)coefficient of correlation
B)coefficient of skewness
C)coefficient of kurtosis
D)coefficient of determination

Question 61

What is probability? What are its characteristics?

Question 62

Briefly discuss the relation between exponential distribution and Poisson distribution with an example.

Question 63

What are the rules that apply when calculating probabilities of events?

Question 64

_____ is a test or series of tests that enables the experimenter to compare two or more methods to determine which is better or determine levels of controllable factors to optimize the yield of a process or minimize the variability of a response variable.

A)Designed experiment
B)Hypothesis testing
C)Kurtosis
D)Regression

Question 65

What is a sampling distribution? State the sampling distributions of
and p for finite populations.

Question 66

The rejection region is chosen so that the probability of the test statistic falling into it,if H₀ is true,is _____.

A)
B)
C)
D)

Question 67

Define binomial and Poisson distributions.State their probability functions.

Question 68

In ANOVA,by dividing the mean square between groups by the mean square within groups,a(n) _____ statistic is computed.

A)t
B)z
C)F
D)R²

Question 69

Suppose that a scatter diagram depicts a relationship between the two variables that can be summarized by a straight line.The correlation coefficient is computed and results in a value of -0.73.Which of the following is NOT TRUE?

A)There is a linear relationship between the two variables.
B)In general,an increase in one variable is associated with an increase in the other variable.
C)In general,an increase in one variable is associated with a decrease in the other variable.
D)Even though the correlation coefficient is less than zero,it still communicates the strength of the linear relationship.

Question 70

An experiment that evaluates the effect of two temperatures (100 and 200 degrees F) and two reaction times (45 and 95 minutes) on process yield has _____ possible combinations to test.

A)2
B)4
C)6
D)8

Question 71

State the steps involved in a hypothesis test.

Question 72

In a designed experiment,a(n) _____ measures the difference that a factor has on the response.

A)main effect
B)factorial
C)treatment
D)interaction

Question 73

In regression analysis,_____ measures the proportion of the variation in the dependent variable that is explained by the independent variable(s).

A)coefficient of correlation
B)an F statistic
C)coefficient of determination
D)regression equation

Question 74

Three scatter diagrams are given below.How many of the diagrams present data that can be described by a linear relationship and,therefore,justifiably summarized by the correlation coefficient?
Plot A
Plot B
Plot C

A)Plot A
B)Plot B
C)Plot A and Plot B
D)Plot A and Plot C

Question 75

The times (in minutes) required by a sample of 15 students to complete a class assigment are given below:
45,42,56,54,40,37,39,45,49,43,45,50,49,55,48
Using Excel functions and calculate the mean,median,mode,range,sample variance,and sample standard deviation.

Question 76

In a factorial experiment,each combination of different levels of the factor is called a(n) _____.

A)main effect
B)response
C)treatment
D)interaction

Question 77

A manager was assigned the task of investigating the error in payments for routine purchases made by the purchasing department.The manager randomly selected 12 payments,investigated them thoroughly,and determined the payment error for each of these payments.The payment error was defined as the difference between the amount paid and what should have been paid.The payment errors determined for these selected payments were as follows:

a.What is the 95% confidence interval for the population mean payment error?
b.Suppose a recent company report inferred that the mean payment error may be running as high as $25.That led the manager to test the null hypothesis that the population mean payment error is equal to $25 versus the alternative that the population mean payment error is not equal to $25.Using a level of significance equal to 0.01,perform this hypothesis test.
c.Suppose another manager used this same data to test the null hypothesis that the population mean payment error is less than or equal to $15 versus the alternative that the population mean payment error is greater than $15.What is the test statistic for this hypothesis testing situation? What is the critical value at a level of significance equal to 0.01? What is the conclusion?

Question 78

_____ is a methodology for drawing conclusions about equality of means of multiple populations.

A)Quality analysis
B)Analysis of variance
C)Correlation analysis
D)Regression analysis

Question 79

In Excel's Histogram tool,how are bins defined?

Question 80

One of the most common types of experimental designs in which all combinations of levels of each factor are considered is called a(n) _____ experiment.

A)combination
B)factorial
C)interaction
D)simple