Simulation Exam 1

Harry Markowitz (one of the big wheels in simulation language development) won his Nobel Prize for portfolio theory in 1990, though the work that earned him the award was conducted much earlier in the 1950s. Who won the 1990 Prize with him? You are allowed to look this one up.

Merton Miller and William Sharpe

Which scenarios are most apt for a steady-state analysis?

Scenarios that deal with long-term phenomena

Ex. We investigate a production line that runs 24/7, we try to estimate the unemployment rate 30 years from now

The Box-Muller method is used to generate what kind of random variable?

Random Normal Variables

X and Y are independent if and only if...

you can write f(x ,y) = a(x)b(y) with no funny limits

What is the most-important theorem in the universe?

Central Limit Theorem

If U 1 and U 2 are i.i.d. Unif(0,1) random variables, what is the distribution of U 1 + U 2? Hints: (i) I may have mentioned this in class at some point; (ii) You may be able to reason this out by looking at the distribution of the sum of two dice tosses; or (iii) You can use something like Excel to simulate U 1 + U 2 many times and make a histogram of the results.

Traingular

Which steps are regarded as essential for a successful simulation study?

Problem formation, model validation, model verification, experimental design, output analysis

Suppose that I have modelled the arriving calls to a call center as a Poisson process. What do I have to carry out in order to determine if that's indeed a reasonable model assumption?

Model validation

Which of the following times could be regarded as events?

Customers arrive, Justin forgets a lyric, Justin sings wrong note, Customers depart

TRUE or FALSE? Customer waiting times are activities because these are typically explicitly specified in the simulation.

FALSE. Although activities are indeed times of specified length,waiting times typically need to be calculated from the sequence of customer arrival and service times | and so are not explicitly specified beforehand.

TRUE or FALSE? The simulation clock time is a variable.

TRUE

TRUE or FALSE? The simulation clock time always equals real time.

FALSE

TRUE or FALSE? In this class, time always moves forward.

TRUE

TRUE or FALSE? A next-event time-advance mechanism is typically used in queueing models involving customer arrivals, services, and departures.

TRUE

TRUE or FALSE? The future events list contains all known upcoming events, including arrival times, departure times, and machine breakdown times.

TRUE

TRUE or FALSE? The FEL can be updated any time an event occurs.

TRUE

TRUE or FALSE? It is possible for the system state to change between consecutive event times.

FALSE

TRUE or FALSE? In a simulation using the "next-event" time-advance mechanism, the simulation clock moves to the most-imminent event.

TRUE

TRUE or FALSE? When a new event occurs, the simulation may update the chronological order of the FEL's events by inserting new events, deleting events, moving them around, or even doing nothing.

TRUE

TRUE or FALSE? Almost every discrete-event computer simulation language maintains a FEL somewhere.

TRUE

In Arena, you are responsible for maintaining the language's FEL.

FALSE

Which is generally the easier simulation modeling approach — Event-Scheduling or Process-Interaction?

Process-Interaction (P-I)

Which is the modeling approach adopted by Arena — Event-Scheduling or Process-Interaction?

Process-Interaction (P-I)

TRUE or FALSE? A simulation language incorporating the P-I approach considers the events that a generic customer undergoes as it passes through the system, and then automatically does the bookkeeping to keep track of how all such customers interact with each other.

TRUE

How many simulation languages are there?

>>50

When selecting a simulation language, what characteristics do you have to take into consideration?

Cost, ease of se, modeling "world view" (ex. P-I), random variate generation capabilities, output analysis capabilities

What sequence of Arena modules would you use to generate customer arrivals, use a server, and then have customers leave the system after they're done with the server?

Create-Process-Dispose

TRUE or FALSE? Arena uses the P-I "world view".

TRUE

TRUE or FALSE? The Basic Process template contains a number of spreadsheets, e.g., a Resource spreadsheet.

TRUE

Which spreadsheets are available in the Basic Process template?

Attribute, Entity, Queue, Resource, Variable

Joe is a customer who needs to go to Point A with probability 0.5, Point B with probability 0.2, and Point C with probability 0.3. Which Decide module option would he use to do so?

N-Way by Chance

TRUE or FALSE? We can use the Assign Module to change an entity's picture.

TRUE

TRUE or FALSE? The system's work-in-process will typically be a variable - not an attribute.

TRUE. Attributes are properties for individual customers; variables are properties of the entire system.

What are properties for the individual customers? (Attribute or Variable)

Attribute

What are properties for the entire system? (Attribute or Variable)

Variable

Which expression will give you the number of customers in the queue called DaveRules.Queue in front of the server called Dave?

NQ(DaveRules.Queue)

You are allowed to do a SEIZE-DELAY sequence in the Arena PROCESS module, but what happens if you forget to eventually add a RELEASE command?

A large queue develops in front of the server.

What are some well-known discrete RVs?

Bernoulli, Binomial, Poisson

What are some well-known continuous RVs?

Uniform, Exponential, Normal

Simulation can be used to analyze queueing models that are too complicated to solve analytically.

TRUE