Operations Management Exam 2

What is the point of SPC charts

Ensure that processes are under control and send out signals when they aren’t

what does X-bar chart measure

tracks changes in the central tendency (mean). Tells if the sample mean is in the control limits

What does the R-chart measure

The dispersion of the sample data. Used to indicate gains or losses in dispersion.

Natural/common causes of variances 

• always present

• expected variation

• output will follow a normal distribution

• variation within limits is considered in control

assigned/special causes of variances

• due to specific changes in the process

• need to identify and fix

Sample size is

the number of observations per sample, not the total number of observations.

Central Limit Theorem

• Distribution of sample means are in control even if process is not

• if only natural causes exist then the output will follow a normal distribution

A normal curve means

• 94.46% of all data points fall between ± 2 standard deviations

• 99.73% of all data points fall within ± 3 standard deviations of the mean.

Process is considered to be in control when

• sample means (x-bar) are within control limits

• sample ranges (r-bar) are within control limits

what does x double bar mean

the mean of sample means

what does sigma x-bar mean

the standard deviation of the mean

what does the variable (z) mean?

the number of standard deviations used for the control limits

what does x bar mean

sample mean

Which type of control chart should be used when it is possible to have more than one mistake per​ item?

• x bar chart

• R bar chart

• C chart

• p chart

 c-chart: counts nonconformities/defects per unit when a unit can have more than one mistake and the sample size is constant.

What is the reasoning behind setting the upper and lower control limits

plus or minus3sigma Subscript x overbar

from the​ mean?

A. 95.45% of the​ time, the sample averages will fall within

plus or minus3sigma Subscript x overbar

if the process has only natural variation.

B. The limits of the Z table are set at

plus or minus3sigma Subscript x overbar.

C. We know that​ 99.73% of natural variation is contained within

plus or minus3sigma Subscript x overbar​,

and thus any data point outside of the limits is likely due to assignable variation.

D. We know that​ 99.73% of assignable variation is contained within

plus or minus3sigma Subscript x overbar​,

and thus any data point outside of the limits is likely due to natural variation.

c: We know that about 99.73% of natural (common-cause) variation falls within ±3σ_{\bar x} for a stable, normally distributed process. So a sample mean outside these limits is unlikely under normal variation and is flagged as assignable cause.

Which of the following would NOT be a concerning pattern on a control​ chart?

A. One point above the upper control limit

B. Two points very near the lower control limit

C. Five consecutive points above the central line.

D.All of the above are concerning patterns on a control chart

Your answer is correct.

ALL are concerning!!!

An operations manager is performing a​ factor-rating analysis to help him choose an outsourcing provider. He is focusing on two​ factors: A and​ B, using a weight of​ 75% for factor A and​ 25% for factor B. He has scored five different potential providers on both​ factors, using a scale of

1minus​5,

with 1 representing the BEST score. Based on the scores provided in the table​ below, which provider should be​ chosen?

The lowest weighted score is better since the highest rating is assigned to the number 1.

• Weights reflect percentage importance.
  Factor A = 75% → 0.75
  Factor B = 25% → 0.25

• Each score is multiplied by its weight.
  For Alpha:
  (1×0.75)+(5×0.25)=0.75+1.25=2.00(1 × 0.75) + (5 × 0.25) = 0.75 + 1.25 = 2.00(1×0.75)+(5×0.25)=0.75+1.25=2.00

Rao​ Technologies, a​ California-based high-tech​ manufacturer, is considering outsourcing some of its electronics production. Four firms have responded to its request for​ bids, and CEO Mohan Rao has started to perform an analysis on the scores his OM team has entered in the table below.

LOADING...

Click the icon to view the table.

Weights are on a scale from 1 through​ 30, and the outsourcing provider scores are on a scale of 1 through 5. The weight for the labor factor is shown as a w because​ Rao's OM team cannot agree on a value for this weight.

Part 2

In the following​ table, the weighted score is computed for each candidate.

🔹 Factor-Rating with Variable Weight (w)

Formula:
Total Score = (Labor × w) + (Total of last 6 criteria)

Provider	Labor	Base (last 6)	Equation
A	2w	395	395 + 2w
B	1w	455	455 + w
C	3w	370	370 + 3w
D	5w	385	385 + 5w

Which of the following is NOT a reason why domestic business operations decide to change to some form of international​ operation?

A.: attract and retain local talent

B.: improve products

C.: improve operations

D.: improve the supply chain

A: to attract and retain local talent

Which of the following is a concern as firms move toward​ globalization?

differences in culture and social behavior

How does an​ organization's strategy relate to its​ mission?

strategy is an action plan to achieve the mission.

Which of the following is the purpose or rationale for an​ organization's existence?

Mission

Competing on cost is

achieving maximum value as perceived by the customer.

A SWOT analysis

identifies an organization’s strengths and weaknesses and its external opportunities and threats.

Which one of the following statements is incorrect regarding globalization and globalization​ strategies?

Part 2

A.

Globalization strategies could contribute to efficiency.

B.

Globalization means​ customers, talent, and suppliers are worldwide.

C.

Globalization strategies could add value to products and services.

D.

Globalization strategies could simplify the operations​ manager's job

D

What are the three main strategies that firms can employ in order to achieve their​ missions?

A.: differentiation, quality​ leadership, and response

B. : productivity, efficiency, and quality leadership

C. : differentiation, cost​ leadership, and response

D. : differentiation, distinctive​ competency, quality​ leadership, and capacity

E. : distinctive​ competency, cost​ leadership, and experience

C: differentiation, cost​ leadership, and response

Which of the following statement is incorrect about the​ mission?

Part 2

A.: The mission statement provides boundaries and focus for organizations.

B.: The mission statement provides the concept around which the firm can rally.

C. : The mission states the rationale for the​ organization's existence.

D.: Each functional area within the firm may develop its own​ strategy, but not its own supporting mission.

Each functional area within the firm may develop its own strategy, but not its own supporting mission.

Competing on differentiation

Part 2

A.: means offering customers a cheaper alternative.

B.: always implies​ higher-quality features.

C.: means offering customers something unique.

D.: only works with physical products.

C: means offering customers something unique

Which of the following is NOT an OM​ strategy/issue during the maturity phase of the product life​ cycle?

A.: long production runs

B.: high production costs

C.: standardization

D.: optimum capacity

B: high production costs

The operations​ manager's job within an organization structure is to

Part 2

A. : implement an OM​ strategy, perform internal​ audits, and increase productivity.

B.: ensure high​ quality, perform internal​ audits, and increase sales.

C.: implement an OM​ strategy, provide competitive​ advantage, and increase productivity.

D.: ensure high​ quality, provide competitive​ advantage, and increase sales.

C: implement, provide competitive advantage, increase productivity

if the true diameter mean should be 155 mm and you want this as your center​ (nominal) line, what are the new

UCL Subscript x overbar

and

LCL Subscript x overbar​?

replace X-bar-bar with 155.

how to calculate the standard deviation of the sample mean?

standard deviation over the sqaure root of n

what is the purpose of SPC (statistical process control)?

ensuring processes meet standards

What are p-bar charts used to measure?

tracks the proportion (p) of items defective. Each item falls into one or another category (good/bad)

For p-bar chart, to determine if process is in control….

take the number of defective/ sample size

The defect rate for your product has historically been about

3.50​%

for p-bar charts, this would represent your p-bar variable. Divide by 100 and plug into the equation.

When are c-charts used?

to count the number of defects. there will be no sample size.