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Work Force Planning. Brandon Blaydes Jonathan Gutierrez Ismael Reyes IE 417 Operations Research II Winter 2011. Work Force Planning Models 17.7. Dr. Parisay’s comme nts are in red. I modified some, but needs some more.
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Work Force Planning Brandon Blaydes Jonathan Gutierrez Ismael Reyes IE 417 Operations Research II Winter 2011
Work Force Planning Models 17.7 • Dr. Parisay’s comments are in red. I modified some, but needs some more. • In our examplewe are interested in the population size in different groups. • It is useful to be able to predict how many people, classified in groups are present in the steady state.
Steady State Census • In steady state census, the idea is: • Number of people entering group during each period = Number of people leaving group during each period.
Steady State Equation • Hi = number hired for groupiat the beginning of each period. • Ni = number in group i at steady state. • Pki= probability of those entering and leaving a certain state.
Equation • Number of people entering group i during each period = Hi + Σk≠iNkpki • Number of people leaving group i during each period = Ni Σk≠ipki • Hence: Hi + Σk≠iNkpki= Ni Σk≠ipki
Problem Statement • Suppose that each American can be classified into one of these four groups: • Children • Working adults • Retired people • Dead
Problem Statement • During a one-year period, .959 of all children remain children, .04 of all children become working adults, and .001 of all children die. • During any given year, .96 of all working adults remain working adults, .03 of all working adults retire, and .01 of all working adults die. • Also, .95 of all retired people remain retired, and .05 of all retired people die. • One thousand children are born each year.
Problem Statement • It is important to notice that for this example we have a type of isolated population since the only group that can enter the system every year are the 1000 new born children. • Also notice how the only absorbing state is Dead, but it can be disregarded since none of the states communicate, and it affects no other state including itself, meaning you can not die twice or be reborn.
Groups i • Group 1 = children,H1=1000 • Group 2 = working adults, H2=0 • Group 3 = retired people, H3=0 • Group 4 = dead, H4=0
System of Equations • In steady state situation we should have: • 1000 = (.04 + .001)N1 (children) • .04N1 = (.03 + .01)N2 (working adults) • .03N2 = .05N3(retiredpeople)
Transition Matrix • Probabilities across the matrix are complimentary
Solutions • Solving the linear system of equations can give us the number of people in each group in each year in steady state situation. Please notice that it is possible that these equations do not have an answer which means steady state does not exists. • N1= 24, 390 • N2= 24, 390.24 • N3 = 14, 634.14
Retiree Pension Fund • Since in the steady state, there are 14, 634.14 retired people, in the steady state they receive 14, 634.14(5,000) dollars per year. Hence, each working adult must pay tax as much as • 14, 634.14(5,000)/ 24, 390.24 = $3,000 per year
Advances in Medicine • Suppose that advances in medical science have reduced the annual death rate for retired people from 5% to 3%. • By how much would this increase the annual taxthat a working adult would pay to cover the pension fund?
Modified Transition Matrix and Equations • 1000 = (.04 + .001)N1 (Children) • .04N1 = (.03 + .01)N2 (Working adults) • .03N2 = .03N3(Retired people)
Solutions • N1=24,390 • N2=24,390.24 • N3=24,400 • 24,400(5,000)/24,390.24 = $5,000 per year
Problem Extension • We believe $5000 a year tax to cover retiree pension fund is too expensive. • Suppose we wanted to reduce the amount of taxan average working adult has to pay by $1000. • We are planning to allow more children into the system and to exile (how?) working adults and retirees out of the system in order to reduce the retiree pension. • How many children would we have to allow and how many adults and retirees would we have to exile per year to reach our goal? (changes are usually made one by one)
Analysis • We will perform analysis by assuming the planned steady state numbers of population in each groups are to be as below. • Children (N1)= 35,000. • Working Adults (N2)= 30,500 • Retired People (N3)= 25,000
Set of Equations • H1 = (.04 + .001)N1 • H1 = (.04 + .001)35000 • H1 = 1435 • H2 + .04N1 = (.03 + .01)N2 • H2 + .04(35000) = (.03 + .01)30500 • H2 = -180 • H3 + .03N2 = .03N3 • H3 + .03(30500) = .03(25000) • H3= -165
Findings • New Pension per adult: • 25000(5,000)/30500 = $4,098 • Our answers indicate that we have to allow 435 more children be born every year. • The negative number inH2indicate that we will have to kick out 180 adults every year!! • The negative number in H3 indicate that we have to kick out 165 retirees every year!!
New Yearly Retiree Pension • With our analysis and our new set of numbers, we have discovered that one of our options to decrease the yearly pension fund by almost $1000 we can: • Allow 435 more children born every year • Exile 180 adults every year • Exile 165 retirees every year • This would allow us to maintain a steady state census with a yearly retiree pension fund of $4098 per working adult.
Conclusions • This type of solution is practical for our problem purposes but not in a real life scenario. • More applicable ways to use this type of problem approach are for example: • if we wanted to determine how many people to hire/lay off from a company. • reduce/increase costs, etc.
