How to measure the dispersion of a random variable


Response to the following question:

1. Random numbers generated by a mathematical process instead of a physical process are pseudorandom numbers.

True

False

4. Experimental outcomes must occur as numerical values in order to define their probability distribution.

True

False

7. Sample information with an efficiency rating of 100% is perfect information.

True

False

8. States of nature should be defined so that one and only one will actually occur.

True

False

12. Identification and definition of a problem

cannot be done until alternatives are proposed.

is the first step of decision making.

is the final step of problem solving.

requires consideration of multiple criteria.

15. In a multicriteria decision problem,

it is impossible to select a single decision alternative.

the decision maker must evaluate each alternative with respect to each criterion.

successive decisions must be made over time.

each of the above is true.

16. Which of the following is not a valid representation of a probability?

35%

0

1.04

3/8

20. In the set of all past due accounts, let the event A mean the account is between 31 and 60 days past due and the event B mean the account is that of a new customer. The union of A and B is

all new customers.

all accounts fewer than 31 or more than 60 days past due.

all accounts from new customers and all accounts that are from 31 to 60 days past due.

all new customers whose accounts are between 31 and 60 days past due.

21. A numerical description of the outcome of an experiment is

a normal variable.

a discrete variable.

a random variable.

an experimental variable.

22. Which of the following are continuous random variables?

I. the weight of an elephant

II. the time to answer a questionnaire

III. the number of floors in a skyscraper

IV. the square feet of countertop in a kitchen

I and II only

I and III only

I, II and IV

I, II, III, and IV

23. A statement that matches the values of a random variable with the probabilities of those values is

the expected value.

the variation of the random variable.

an experiment.

a probability distribution.

24. In order to measure the dispersion of a random variable, look at its

standard deviation.

mean.

expected value.

average.

25. Experiments with repeated independent trials will be described by the binomial distribution if

the trials are continuous.

each trial result influences the next.

the time between trials is constant.

each trial has exactly two outcomes whose probabilities do not change.

26. The options from which a decision maker chooses a course of action are

called the decision alternatives.

under the control of the decision maker.

not the same as the states of nature.

each of the above is true.

27. States of nature

can describe uncontrollable natural events such as floods or freezing temperatures.

can be selected by the decision maker.

cannot be enumerated by the decision maker.

each of the above is true.

28. A payoff

is always measured in profit.

is always measured in cost.

exists for each pair of decision alternative and state of nature.

exists for each state of nature.

30. A decision tree

presents all decision alternatives first and follows them with all states of nature.

presents all states of nature first and follows them with all decision alternatives.

alternates the decision alternatives and states of nature.

arranges decision alternatives and states of nature in their natural chronological order.

31. Time series methods

discover a pattern in historical data and project it into the future.

include cause-effect relationships.

are useful when historical information is not available.

each of the above is true.

32. Gradual shifting of a time series over a long period of time is called

periodicity.

cycle.

regression.

trend.

33. Seasonal components

cannot be predicted.

are regular repeated patterns.

are long runs of observations above or below the trend line.

reflect a shift in the series over time.

38. In assigning random numbers to probabilistic events in a simulation,

several events are associated with the same random number

every random number is associated with a particular event

every event is associated with the same random number

all of the above

39. A researcher wants to simulate sunny and rainy days in her town for a 3-week period. What is the minimum number of digits the student must obtain from a random number table for each observation if it rained on two-fifths of the days over the past several years at this time of the year? Assume that days can be classified historically as either sunny or rainy.

1

2

3

all of the above.

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Basic Statistics: How to measure the dispersion of a random variable
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