Supplement B  Simulation

Supplement

B / Simulation

TRUE/FALSE

  1. Simulation is the process of reproducing the behavior of a system using a model that describes the processes of the system.

Answer: True

Reference:Reasons for Using Simulation

Difficulty: Easy

Keywords: simulation, system, behavior, model

  1. Time compression is the feature of simulation that allows managers to obtain operating-characteristic estimates in much less time than is required to gather the same operating data from a real system.

Answer: True

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: time, compression

  1. Simulation can be used to sharpen managerial decision making.

Answer: True

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: simulation, manager, decision

  1. Decision variables are random events that the decision maker cannot control.

Answer: False

Reference: The Simulation Process

Difficulty: Moderate

Keywords: decision, variable

  1. A statistically significant difference in simulation results, when acted upon by the operations manager, will result in significant process improvements in the eyes of the customer or company or both.

Answer: False

Reference: The Simulation Process

Difficulty: Moderate

Keywords: statistically, managerially, significant, results

  1. Steady state occurs when the simulation is repeated over enough time that the average results for performance measures remain constant.

Answer: True

Reference:Computer Simulation

Difficulty: Moderate

Keywords: steady, state, simulation

MULTIPLE CHOICE

  1. A simulation model:
  2. describes operating characteristics with known equations.
  3. replicates the service of customers and keeps track of characteristics such as the number in line, the waiting time, and the total time in the system.
  4. prescribes what should be done in a situation.
  5. finds the optimal solution to a problem without having to try each alternative.

Answer: b

Reference:Reasons for Using Simulation

Difficulty: Easy

Keywords: simulation, model

  1. Simulation models are:
  2. useful when waiting-line models are too complex.
  3. useful for conducting experiments using the real system.
  4. preferred because they find optimal solutions.
  5. usually inexpensive relative to other approaches.

Answer: a

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: simulation, model, waiting, line

  1. A manager has been given the table shown below and is asked to generate random numbers. Which of the following statements is TRUE?

Range / # Customers
00–49 / 0
50–79 / 1
80–99 / 2
  1. There are no customers in the store 49 percent of the time.
  2. The probability of having one customer in the store is 0.30.
  3. The relative frequency of having two customers in the store is 0.80.
  4. If we randomly choose the numbers 0 through 99 enough times, about 99 percent of the time we will have two customers in the store.

Answer: b

Reference: The Simulation Process

Difficulty: Easy

Keywords: random, number, frequency, probability

  1. Using a simulation model to gather a year of operating data in a few minutes is known as:
  2. historical search data collection.
  3. Monte Carlo optimization.
  4. suboptimization.
  5. time compression.

Answer: d

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: time, compression

  1. Which one of the following relationships is correct?
  2. Decision variables reflect the value of uncontrollable variables.
  3. Dependent variables reflect the value of decision and uncontrollable variables.
  4. Uncontrollable variables reflect the value of decision variables.
  5. Uncontrollable variables reflect the values of dependent variables.

Answer: b

Reference: The Simulation Process

Difficulty: Moderate

Keywords: decision, uncontrollable, dependent, variable

  1. A number that has the same probability of being selected as any other is called a(n):
  2. Monte Carlo number.
  3. decision number.
  4. uncontrolled number.
  5. random number.

Answer: d

Reference: The Simulation Process

Difficulty: Moderate

Keywords: random, number

  1. The manager of a branch bank wants to build a simulation model of the lobby operation to reduce the waiting time of her customers. The number of tellers is an example of:
  2. a decision variable.
  3. an uncontrollable variable.
  4. a time-compressed variable.
  5. a dependent variable.

Answer: a

Reference: The Simulation Process

Difficulty: Moderate

Keywords: decision, variable

  1. The manager of a branch bank wants to build a simulation model of the lobby operation to reduce the waiting time of her customers. The number of customers arriving at any point of time is an example of:
  2. a decision variable.
  3. an uncontrollable variable.
  4. a time-compressed variable.
  5. a dependent variable.

Answer: b

Reference: The Simulation Process

Difficulty: Moderate

Keywords: uncontrollable, variable

  1. The manager of a branch bank wants to build a simulation model of the lobby operation to reduce the waiting time of her customers. The number of customers waiting in line at any point of time is an example of:
  2. a decision variable.
  3. an uncontrollable variable.
  4. a time-compressed variable.
  5. a dependent variable.

Answer: d

Reference: The Simulation Process

Difficulty: Moderate

Keywords: dependent, variable

  1. Which one of the following statements regarding simulation analysis is FALSE?
  2. Simulation analysis is a form of hypothesis testing.
  3. Analysis of variance is a commonly used statistical method for simulation analysis.
  4. Statistical methods require the replication of simulation runs.
  5. Each time a simulation model is run for a given set of decision variables, the same random numbers must be used.

Answer: d

Reference: The Simulation Process

Difficulty: Hard

Keywords: random, number

  1. Which one of the following statements about simulation analysis is FALSE?
  2. If a result is statistically significant, it is always managerially significant.
  3. Simulation analysis is a form of hypothesis testing.
  4. Analysis of variance is a commonly used statistical method for simulation analysis.
  5. Statistical methods require the replication of simulation runs.

Answer: a

Reference: The Simulation Process

Difficulty: Hard

Keywords: simulation, statistically, manager, significant

  1. A simulation model is used to test the impact of the number of sample customers at a supermarket. As the model is run, the decision maker watches the average number of customers in the store rapidly increase from zero until it levels off and holds a constant value. The simulation model is:
  2. not valid due to the lack of change.
  3. in steady state.
  4. not valid due to the fluctuation in the statistics.
  5. a random variable.

Answer: b

Reference: Computer Simulation

Difficulty: Moderate

Keywords: steady, state

  1. Excel can be used to perform:
  2. discrete, next-event simulation.
  3. continuous simulation.
  4. analog simulation.
  5. Monte Carlo simulation.

Answer: d

Reference: Computer Simulation

Difficulty: Moderate

Keywords:Monte Carlo, simulation

  1. Which of these is a special simulation language?
  2. C++
  3. FORTRAN
  4. SLAM
  5. VISUAL BASIC

Answer: c

Reference: Computer Simulation

Difficulty: Moderate

Keywords: simulation, language

  1. The arrival of customers at a lemonade stand is modeled in SimQuick using a(n):
  2. entrance block.
  3. buffer block.
  4. workstation block.
  5. decision point.

Answer: a

Reference: Computer Simulation

Difficulty: Moderate

Keywords: SimQuick, block, entrance

  1. A patient’s interminable wait for the first available physician is modeled in SimQuick using a(n):
  2. entrance block.
  3. buffer block.
  4. workstation block.
  5. decision point.

Answer: b

Reference: Computer Simulation

Difficulty: Moderate

Keywords: SimQuick, block, buffer

FILL In The BLANK

  1. ______is the act of reproducing the behavior of a system using a model that describes the processes of the system.

Answer: Simulation

Reference:Reasons for Using Simulation

Difficulty: Easy

Keywords: simulation, model, system

  1. ______is a feature of simulation models that allows them to obtain operating-characteristic estimates in much less time than is required to gather the same operating data from a real system.

Answer: Time compression

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: time, compression

  1. ______uses random numbers to generate simulation events.

Answer: Monte Carlo

Reference: The Simulation Process

Difficulty: Moderate

Keywords:Monte Carlo, random, simulation

  1. The two approaches to data collection for simulation are ______and ______.

Answer: statistical sampling, historical search

Reference: The Simulation Process

Difficulty: Moderate

Keywords: statistical, sampling, historical, search, data, collection

  1. A number that has the same probability of being selected as any other number is a(n) ______.

Answer: random number

Reference: The Simulation Process

Difficulty: Moderate

Keywords: random, number, probability

  1. A variable that is controlled by the decision-maker and will change from one run to the next as different events are simulated is a(n) ______..

Answer: decision variable

Reference: The Simulation Process

Difficulty: Moderate

Keywords: decision, variable, controlled

  1. ______are random events that the decision maker cannot control.

Answer: Uncontrollable variables

Reference: The Simulation Process

Difficulty: Moderate

Keywords: uncontrollable, variable, random

  1. ______occurs when the simulation is repeated over enough time that the average results for performance measures remain constant.

Answer: Steady state

Reference:Computer Simulation

Difficulty: Moderate

Keywords: steady, state

SHORT ANSWERS

  1. What is the difference between a waiting-line model as described in Supplement C and a simulation model of a waiting-line problem?

Answer: The waiting-line model describes the operating characteristics of interest with known equations. The simulation model actually mimics the arrival of customers and their service, empirically calculating the operating characteristics.

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: simulation, model, waiting, line

  1. What is meant by time compression in a simulation model?

Answer: Simulation models gather data on operating characteristics in much less time than gathering the same data from the real system.

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: time, compression

  1. What are the motivations for using simulation for analyzing processes?

Answer: Simulation models are useful when waiting-line models are too complex. When the relationship between variables is nonlinear, or when there are too many variables or constraints to handle with optimizing approaches, simulation is an attractive option. Simulation can be used to conduct experiments without disrupting the real system. Simulation can also be used to discover operating characteristics of a system in much less time than the data could be gathered from the real system. Finally, simulation can be used to sharpen managerial decision making through gaming.

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: simulation, time, compression, model

  1. Why is simulation considered the method of last resort?

Answer: Optimizing models would be preferred because they find the best solution when they can be applied. Simulation models use a trial-and-error approach to problem solving where the analyst must prescribe the alternatives to evaluate. In addition, simulation models are expensive to build.

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: optimizing, simulation

  1. What are the differences between decision variables and uncontrolled variables? Describe the differences and provide an example from a simulation model.

Answer: A decision variable is one that is under control of the decision maker and will change from one simulation run to the next as different events are simulated. Uncontrolled variables are random events that the decision maker cannot control. Both are functions of random numbers in the simulation model, but the decision maker realizes that the uncontrolled variables, such as weather, customer arrival patterns, state of the economy, and so on are outside his influence. Examples will vary.

Reference: Reasons for Using Simulation

Difficulty: Moderate

Keywords: decision, variable, uncontrolled

  1. As the operations manager of the bookstore on your college campus, you are keenly aware of the seasonality of demand for your wares. At the start of each semester you puzzle over the number of checkout clerks to schedule and finally decide to model your predicament using Monte Carlo simulation. Describe the simulation process and indicate what assumptions you must make at each step.

Answer: The simulation process consists of data collection, random number assignment, model formulation, and analysis.

In the data collection step you should capture information on the arrival patterns of your customers, their shopping times, and the checkout times for your clerks. If you choose to sample for each of these variables you must decide how many observations to take and when to take them. One assumption you will make is whether to treat each day of the week and the entire day the same. Is it safe to assume that the same number of customers arrive on a Monday as on a Wednesday and do the same number of customers arrive at 8 a.m. as arrive at 1 p.m.? Are service times fairly constant for the number of items purchased and does the number of items vary by time of day?

In the random-number assignment step

Reference: The Simulation Process

Difficulty: Moderate

Keywords: Monte Carlo, simulation, process

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