DSCI Final Exam

The c-chart signals whether there has been a: a. gain or loss in uniformity. b. change in the number of defects per unit. c. change in the central tendency of the process output. d. change in the percent defective in a sample. e. change in the AOQ.

b

Control charts for variables are based on data that come from: a. acceptance sampling. b. individual items. c. averages of small samples. d. averages of large samples. e. the entire lot.

c

Jars of pickles are sampled and weighed. Sample measures are plotted on control charts. The ideal weight should be precisely 11 oz. Which type of chart(s) would you recommend? a. p-chart b. c-chart c. both an x-bar chart and an R-chart d. an x-bar chart, but not an R-chart e. both a p-chart and a c-chart

c

Which of the following most requires long-range forecasting (as opposed to short-range or medium-range forecasting) for its planning purposes? a. job scheduling b. production levels c. cash budgeting d. capital expenditurese. purchasing

d

What is the statistical process chart used to control the number of defects per unit of output? a. x-bar chart b. R-chart c. p-chart d. AOQ chart e. c-chart

e

MAPE

Average of absolute differences between forecast and actual expressed as a % of actual values Expresses the error as a percent of the actual values.

Mistakes stemming from workers' inadequate training represent a natural cause of variation. (True or False)

False. Mistakes stemming from workers' inadequate training represent a assignable cause of variation.

A process is said to be in statistical control when assignable causes are the only sources of variation. (True or False)

False. A process is said to be in statistical control when natural causes are the only sources of variation.

A process mean chart illustrates the amount of dispersion within the samples. (True or False)

False. A process range chart illustrates the amount of dispersion within the samples.

A p-chart is appropriate to plot the number of typographic errors per page of text. (True or False)

False. The c-chart is not appropriate to plot the number of typographic errors per page of text.

The purpose of process control is to detect when natural causes of variation are present. (True or False)

False. The purpose of process control is to detect when assignable causes of variation are present.

Risks & Mitigation Tactics: Quality Failures

Implement extensive controls and certifications for suppliers.

Make-Or-Buy Decision

Involves deciding whether to produce a product internally or to purchase it from an external source. This decision impacts the strategic design of the supply chain.

Sourcing Strategies:

Many Suppliers Few Suppliers Vertical Integration Joint Ventures Keiretsu Networks Virtural Companies

If the process average is in control, then the process range _________________.

May or may not be in control

One use of short-range forecasts is to determine production levels. (True or False)

True

The smaller the number of periods in the simple moving average forecasting method, the greater the method's responsiveness to changes in demand. (True or False)

True

The smaller the standard error of the estimate, the more accurate the forecasting model. (True or False)

True

Risks & Mitigation Tactics: Supplier Failures

Use multiple suppliers to mitigate the risk of one failing to deliver.

Sourcing Strategies: Joint Ventures

Used to reduce risk and enhance product prowess or technological skills

Forecasts are usually classified by time horizon into which three categories? a. short-range, medium-range, and long-range b. finance/accounting, marketing, and operations c. strategic, tactical, and operational d. exponential smoothing, regression, and time series e. departmental, organization, and industrial

a

The local newspaper receives several complaints per day about typographic errors. Over a sevenday period, the publisher has received calls from readers reporEng the following total daily number of errors: 4, 3, 2, 6, 7, 3, and 9. Based on these data alone, what type of control chart(s) should the publisher use? a. p-chart b. c-chart c. x-bar chart d. R-chart e. x-bar chart and R-chart

b

Up to three standard deviations above or below the centerline is the amount of variation that statistical process control allows for: a. Type I errors. b. about 95.5% variation. c. natural variation. d. all types of variation. e. Assignable variation.

c

A fundamental distinction between trend projection and linear regression is that a. Trend projection can be a function of several variables, while linear regression can only be a function of one variable. b. Trend projection uses the method of least squares while linear regression does not. c. Only linear regression can have a negative slope. d. In trend projection the independent variable is time; in linear regression the independent variable need not be time, but any variable with explanatory power.

d

The number of defects of a hotel room cleaning (sheets not straight, smears on mirror, missed debris on carpet, etc.) should be measured using what type of control chart? a. x-bar chart b. R-chart c. p-chart d. c-chart e. either x-bar chart or R chart

d

Which of the following is TRUE of a p-chart? a. The lower control limit is found by subtracting a fraction from the average number of defects. b. The lower control limit indicates the minimum acceptable number of defects. c. The lower control limit equals D3 times p-bar. d. The lower control limit may be at zero. e. The lower control limit is the same as the lot tolerance percent defective.

d

Which of the following statements regarding critical paths is TRUE? a. The shortest of all paths through the network is the critical path. b. Some activities on the critical path may have slack. c. Every network has only one critical path. d. On a specific project, there can be multiple critical paths, all with the same duration. e. The duration of the critical path is the average duration of all paths in the project network.

d

An x-bar control chart was examined, and no data points fell outside of the limits. Can this process be considered in control? a. Not yet, there could be a pattern to the points. b. Not yet, the R-chart must be checked. c. Not yet, the number of samples must be known. d. Yes. e. Both A and B.

e

Assignable causes: a. are not as important as natural causes. b. is within the limits of a control chart. c. depend on the inspector assigned to the job. d. is also referred to as "chance" causes. e. are causes of variation that can be identified and investigated

e

Plots of sample ranges indicate that the most recent value is below the lower control limit. What course of action would you recommend? a. Since there is no obvious pattern in the measurements, variability is in control. b. One value outside the control limits is insufficient to warrant any action. c. Lower than expected dispersion is a desirable condition; there is no reason to investigate. d. The process is out of control; reject the last units produced. e. Variation is not in control; investigate what created this condition.

e

Which of the following is NOT a type of qualitative forecasting? a. jury of executive opinion b. sales force composite c. market survey d. Delphi method e. moving average

e

The critical path can be determined by use of either the "forward pass" or the "backward pass." (True or False)

- False - The critical path can be determined by use of either the "forward pass" AND the "backward pass."

Identify four quantitative forecasting methods:

1. Naive 2. Moving Average 3. Exponential Smoothing 4. Trend projection (Linear Regression)

Gradual upward or downward movement of data over time is called:

A trend

Long-Range Time Horizon

Are used in planning new products, capital expenditures, and facility location or expansion.

MSE

Average of the squared differences between forecast and observed values

Sourcing Strategies: Vertical Integration

Can be either forward (selling directly to consumers) or backward (buying suppliers) to control more of the supply chain.

Sourcing Strategies: Keiretsu Networks

Combines features of vertical integration and few suppliers, typical in south Korean companies.

What is the objective of critical path analysis?

Determines the Longest Path through a network of activities. The Longest path is the key to making the schedule that provides for completing all activities in the shortest time. These activities are identified by management.

Risks & Mitigation Tactics: Information Loss

Employees, redundant, databases, and ensures all parties understand the data.

Sourcing Strategies: Many Suppliers

Encourages competition among suppliers to achieve lower costs.

In AON network diagrams, arrows represent activities. (True or False)

False. - In AOA network diagrams, arrows represent activities.

A p-chart is appropriate to plot the number of typographical errors per page of text. (True or False)

False. A c-chart is appropriate to plot the number of typographical errors per page of text.

Forecasts are always based on quantitative models that use historical data to forecast future demand. (True or False)

False. Based on quantitative and Qualitative approaches.

If the process average is in control, then the process range must also be in control. (True or False)

False. If the process average is in control, then the process range may or may not be in control.

Mean charts and range charts may substitute for one another, and only one of them needs to be used to determine if a process is in control. (True or False)

False. Mean and range control charts must be used together.

A forecast with a time horizon of about 3 months to 3 years is typically called a long-range forecast. (True or False)

False. Medium Range Forecast

Mistakes stemming from workers' inadequate training represent an unassignable cause of variation. (True or False)

False. Mistakes stemming from workers' inadequate training represent an assignable cause of variation.

Processes with high quality will have no variability. (True or False)

False. Processes with high quality will have some degree of variation (natural)

Sourcing Strategies: Few Suppliers

Focuses on building long-term relationships and technological advances.

Is a quality control chart that indicates when changes occur in the dispersion of a production process.

Range Chart

The ___________ is a quality control chart that indicates when changes occur in the dispersion of a production process.

Range Chart

Outsourcing

Refers to transferring tradition internal activities and resources to external vendors. This approach is often used to focus on core competencies and reduce costs.

Forecasts that only work well if we can assume that market demands will stay steady over time.

Simple Moving Average

MAD

Sum of absolute values of all errors / # of periods

What falls under risks and mitigation tactics?

Supplier Failures Quality Failures Logistics Delays Information Loss Natural Catastrophes, Theft, Political Issues

Sourcing Strategies: Virtual Companies

These companies rely heavily on a variety of supplier relationships, focusing on management expertise and operational efficiency.

The use of linear regression is an example of an associative model of forecasting. (True or False)

True

Risks & Mitigation Tactics: Logistics Delays

Use multiple transportation modes and back up plans.

Risks & Mitigation Tactics: Natural Catastrophes, Theft, Political Issues

Uses insurance and diversifies supplier locations.

If a sample of items is taken and the mean of the sample is outside the control limits, the process is: a. likely out of control and the cause should be investigated. b. in control, but not capable of producing within the established control limits. c. within the established control limits with only natural causes of variation. d. monitored closely to see if the next sample mean will also fall outside the control limits. e. producing high-quality products.

a

To set the x-bar chart upper and lower control limits, one must know the process central line, which is the: a. average of the sample means. b. total number of defects in the population. c. percent defects in the population. d. size of population. e. average range.

a

A manufacturer uses statistical process control to control the quality of the firm's products. Samples of 50 of Product A are taken, and a defective/acceptable decision is made on each unit sampled. For Product B, the number of flaws per unit is counted. What type(s) of control charts should be used? a. p-charts for both A and B b. p-chart for A, c-chart for B c. c-charts for both A and B d. p-charts for A, mean and range charts for B e. c-chart for A, mean and range charts for B

b

As compared to long-range forecasts, short-range forecasts: a. is less accurate. b. deal with less comprehensive issues supporting management decisions. c. employ similar methodologies. d. all of these e. none of these

b

According to the text, what is the most common choice of limits for control charts? a. ± 1 standard deviation b. ± 2 standard deviations c. ± 3 standard deviations d. ± 3 standard deviations for means and ± 2 standard deviations for ranges. e. ± 6 standard deviations

c

If two variables were perfectly correlated, what would be the correlation? a. -1 b. 0 c. 1 d. A or C e. 2

d

Natural variations: a. affects almost every production process. b. are the many sources of variation that occur when a process is under control. c. when grouped, form a pattern, or distribution. d. are tolerated, within limits, when a process is under control. e. All of these.

e

Processes with high quality will have ____________.

some degree of variation (natural)

Identify the three primary functions of all organizations:

1. Marketing 2. Finance / Accounting 3. Production / Operations

What is the difference between natural and assignable causes of variation?

Natural variation affects every production process. It is expected and it cannot be reduced. Assignable variation can be traced back to specific causes.

A c-chart is appropriate to plot the number of flaws in a bolt of fabric. (True or False)

True

In trend projection, the regression slope can be either positive or negative. (True or False)

True