Q1 In connection with a program that provides alternatives for youth who have a run in with the criminal justice system, a colleague mentions that the program could be more effective if there were an easy way to predict who might benefit from the alternative program. The data suggests that about 75% of the youth in Ourtown are "good kids" who would benefit from the alternative program and 25% are "bad kids" who will not. Your supervisor also says you should come up with some more acceptable terms than "good" and "bad."
Q2 Sketch, anew, the decision tree for the embassy party described in the text book.
"The officer in charge of a United States Embassy recreation program has decided to replenish the employees club funds by arranging a dinner. It rains nine days out of ten at the post and he must decide whether to hold the dinner indoors or out. An enclosed pavilion is available but uncomfortable, and past experience has shown turnout to be low at indoor functions, resulting in a 60 per cent chance of gaining $100 from a dinner held in the pavilion and a 40 per cent chance of losing $20. On the other hand, an outdoor dinner could be expected to earn $500 unless it rains, in which case the dinner would lose about $10" (Stokey & Zeckhauser 1977, 202).
Q3 What is the expected value of a two dice toss if the payoff is whatever comes up on the dice, in dollars? Sketch this as a decision tree with just chance nodes.
Q4.Along with the alternative arrest program, a town is considering a mix of extra community policing, after school programs and evening youth programs as a part of their comprehensive efforts.
Q71. Consider this little bit of logic that describes a tourist's thinking process (taken from the title of a 1970s movie): “if it’s Tuesday, this must be Belgium. Otherwise, I have no idea where we are.” Sketch a flowchart that represents this flow of thought.
Q72. Sketch a flowchart that represents this bit of logic: “if you are a woman then if you are over 40 you should have this test no matter what but if either parent had diabetes women should have the test no matter what. Men only need to take the test if they are overweight.”
Q73. Sketch a flowchart that represents this bit of logic: “if cell E$3 is greater than cell G$12 then value is G$12; otherwise, value is G$12-E$3.”
Q74. Sketch a flowchart that represents this bit of logic: “if the balance is less than the minimum alternative payment then just pay the balance, otherwise, pay the minimum alternative payment.”
Q75. Sketch a flowchart that represents this bit of logic: “If you can get a direct flight for under $1500 take it unless it leaves from SFO before 9 am. Otherwise, see if anything is available on frequent flier miles no matter what the routing. If you can’t find anything, use Expedia to find the cheapest flight out of OAK.”
Q76. Sketch a flowchart that represents this bit of logic: If I have anything that is due tomorrow then if I am acing the class already and if I have some money I’ll go out drinking by myself (since all my friends will be busy), but if I don’t have any money I’ll stay home and watch reruns on cable. If, on the other hand, I’m not acing this class, I’ll stay home and study. If I don’t have anything due tomorrow, then if I have some money I’ll see if some friends are around and if so I’ll party with them. Otherwise, I’ll drink alone. If I don’ t have any money I’ll just stay home and watch reruns on cable.
Q77. Draw a flow charts that represents "Do A until B" and "While B do A. Then do C".
Q78. Sketch a flow chart that represents the following writing protocol: (1) Edit your essay until it is perfect. (2) While the essay still needs work, edit your essay.
Q79. Use stepwise refinement to create a flow chart for this set of instructions: Do A and then B. If C, then while E do F and after that do G, otherwise do H. Do I.
Q80. If A: until B do C and then, do D if E, otherwise do F while G. Otherwise if H, then if I do J else do K. Do L.
Q81. Is a picture worth 548 words? Convert the Rock County, Wisconsin "Drug Court Flow Chart" from text form to diagram form.
Q82. Flow chart the following protocols. (a) Record youth name and address. Check in system to see if already there. If there, pull up record and verify information. If not, create new record and ask for information. When done, send record to orientation staff, give youth a number and instruct to wait until number is called. (b) Once stage three in the treatment regimen is completed, clients are not eligible for the next stage in treatment until they have had three consecutive clean weekly drug tests. If they have one failed test they are given a warning. Two failed tests in a row and they have to meet with a counselor. Three failed tests and they are out of the program.
Q83. Weimer & Vining (1989) characterize policy problems in terms of market failure and government failure. Any given problem, they suggest, can be placed in one of four categories: (1) market AND government failure; (2) government works (policy corrects for market failure); (3) market works; (4) government failure to correct for market failure. Their suggested strategy is to start by asking whether there is a market failure and then whether there is government failure. Using the two conditionals, "Is there evidence of market failure?" and "Is there evidence of government failure?" construct a flowchart that would permit you to classify any given situation into one of the four aforementioned categories.
Q84. If the weather is nice, plant a garden. Otherwise paint the office. For the garden, make a decision between flowers and vegetables. If you go for vegetables, buy compost, seeds, and stakes; till the soil, and hook up the irrigation. If it's flowers this year, go to the garden store and if they have 4 inch plants buy enough for the plot and plant them. If they don't then get flats of smaller plants and bring them home and let them get acclimated for a week and then plant them next week. To till the soil, if the ox is healthy, do it with the animal plow, otherwise get out the rototiller.
Q85. A regimen consists of three mandatory sessions, followed by an optional weekend retreat and then, monthly sessions until standard test indicates absence of symptoms.
Q86. Sort clients into four categories promising, troubling, recalcitrant, hopeless on the basis of two tests which can be passed or failed.
Q87. Sketch a flow chart to represent the following scenario. The Alameda County Waste Management Authority (ACWMA) has decided to spend some money on a public relations campaign to increase the level of composting ("green bin") recylcing. Data on hand says that current levels are 4 kg per household of four per week. The plan is to spend $10,000 on advertising each month until the level has gone over 6 kg per week for four weeks in a row.
Prefatory concern – what does 4 kg / household of 4 / week mean? The amount of compost likely depends on the number of people in a household. We don't want to get the numbers wrong by failing to take this into account. So, in our data collection, we double the number for households of 2, halve it for households of 8, etc. Why not just express it as "kg/person/week"? That would work fine mathematically. Perhaps the PR folks had wanted to focus on households (and families) so as to induce a greater sense of collective responsibility.
Q88. Convert the following statement to “pseudo-Excel” formulas (follow the example to see what we mean by that).
Example. "If it is Tuesday, this must be Belgium, otherwise it is France" would become something like
Q89. Convert the following statement to “pseudo-Excel” formulas (follow the example to see what we mean by that).
Example. "If it is Tuesday, this must be Belgium, otherwise it is France" would become something like
Q90. Convert the following statement to “pseudo-Excel” formulas (follow the example to see what we mean by that).
Example. "If it is Tuesday, this must be Belgium, otherwise it is France" would become something like
Q91. Sketch flow chart that captures logic of the following process.
Q92. What is wrong with the decision tree here? I need to decide whether to work at home or go down to Stanford today. At home, because of distractions, I work at about 75% efficiency. If I go to my research office at Stanford I work at 100% efficiency. If I work at home I will get 8 hours to work. If I decide to drive down to Stanford, I will get 8 hours minus driving time to work. The normal drive is ^0 minutes each way. But about 20% of the time it is extra light and the round trip takes just 90 minutes. About 30% of the time, though, traffic is awful and round trip is 180 minutes. I made a decision tree to figure out where I should work if I am trying to maximize my output, but I did something wrong. Fix the tree and tell me what I should do.
Q93. A new device at your favorite big box store costs $200. It has a one year guarantee from the manufacturer. The cashier offers you a special deal on a three year replacement warranty (assume it's good, will be honored, etc.) — $40. You estimate that the chances of the device failing during second and third years is 25% and that the price of replacement by then will be $150. Should you buy the service plan? What are the parameters of this decision model?
Q94. Assuming you are self-interested, what makes more sense: buy a $1.00 lottery ticket with a 1 in five million chance of winning a million dollars, buying a twenty dollar raffle ticket for a local fundraiser with a 1 in 2500 chance of winning a $500 jackpot, or playing a $1 stake game of rock-scissors-paper with the person next to you.
Q95. You never know what the weather is going to be around here. Somedays you need a sweater and some days you need sunglasses. The smart person, they say, always brings both. But suppose there is a definite hassle involved in bringing either (e.g., you ride a bike and space is tight). Sketch a decision tree that takes into account a cost to bringing either and a cost to not having either when you need them and the possibility that on a given day you might need one, the other, or both. Use plausible numbers of your own choice.
Q96. A college enrolls two types of students. Full-pay students pay $40K tuition and half-pay students pay $20K. At present the school spends $1 million per year to recruit 200 students about 75% of whom are half-pay and 25% full-pay. A consultant submits a proposal to shift resources around and use GIS to target recruitment at zip codes that are more likely to yield full-pay students. She says there is a 75% chance that the results will be a slightly smaller class (190) but one with 40% full-pay and 60% half-pay. Unfortunately there is also a risk things won't turn out so well. There's a 25% chance that enrollment will drop to 170 and only 30% will be full pay. Use a decision tree to advise the college as to its best course of action.
Q97. There's an idea in philosophy called "Pascal's Wager" that describes a way of thinking about the existence of god. It goes like this. I have a choice to believe or not believe. And there is a chance that god exists and a chance that there is no god. If I believe and there is a god, I have a chance at eternal salvation. If I don't believe but there is a god, I suffer eternal damnation. If I do believe and it turns out there is no god, I will feel a bit of a chump, but the atheists can feel smug if opposite is the case. Sketch this situation as a decision tree. Should you believe in god?
Q98. Sketch the decision tree for the following scenario. I want to buy a used car. The car I am looking at is being offered at $4000. The seller says it is in good shape all around. I look it over and agree, but you never know for sure. Suppose there is a 10% chance that it is a total dog and that buying it will be a $2000 mistake. I know a mechanic who will give it a very thorough inspection, for a price. If my assumptions are correct, what's the most I should pay my mechanic?
Q99. We want to apply for a home equity line of credit. The bank says it has to know what your house is worth (It has to be worth a certain amount over what we still owe on the mortgage to get a loan at a good rate). A loan at a bad rate will cost $10,000 more than a loan at a good rate. We think there is a 60:40 chance that our house is in fact worth enough to get a good rate. We have a choice between a cheap appraisal ($100) and an expensive appraisal ($1000). A cheap appraisal, we have learned, has a 40% chance of correctly valuing a property. An expensive appraisal is right 70% of the time. Draw a decision tree that will help us figure out what to do.
Q100. How much would you be willing to pay for a forecast that would resolve the contingency in problem 95?
Q101. If the farmer plants early and the spring is warm, she can get a 20% increase in her harvest. But if she plants early and there's a late frost she can lose 50% of her harvest. Historically, these late frosts happen one year in four (25% of the time). Use a decision tree to determine how much she would be willing to invest in a perfect forecast.
Q102. Kids these days! Of those who get into trouble, it turns out, about 30% are "real trouble-makers" who need some help. The other 70% are normal adolescents who will age out of their trouble-making under normal care. A social worker friend introduces you to a test that you can give to kids who are referred to you to determine which category they are in. Research has suggested the test is 75% accurate. Use tree flipping to describe what to make of the test's results.
Q103. Suppose we are running a program to which we want to accept only individuals in the top 25% of the population (on some measurable trait). Unfortunately, our test for measuring the trait is only 80% accurate. Draw event tree and flip to show what kind of faith we can have in the test results. Which test result appears more worthy of taking at face value? Which group would you be inclined to develop a second test for?
Q104. House gets another case. There's this funny rash. We won't say where it appears, but it's a funny rash. In 1% of the cases, it means something really, really bad — anxoreisis. Fortunately, there's a test. Unfortunately, it's not a perfect test. Fortunately, it's a pretty good test. Unfortunately, it is wrong 2% of the time. Work it out.
Q105. Following on problem 104, suppose the test is not painless or without its own risks. Suppose the "cost" of the test is 5. And suppose the treatment is also not so nice and the cost of the treatment is 15. But if you have the disease and you are not treated, the results are nasty : 50. Do we have enough information to recommend a course of action? What should we do?
Q106. She may love you or she may not. It turns out there is a 40% chance she does. You decide to use the buttercup test to find out (hold a buttercup under chin and see if it reflects yellow). The test is 90% accurate. Draw tree and flip to determine what conclusions we can draw from positive and negative buttercup test results.
Q123. Suppose I am sitting on $20,000 and I am trying to figure out whether or not to use it to buy a car. I have a very limited life and have determined that if I buy the car I will have to pay $800 insurance and about 10 cents per mile to operate it and I drive 2500 miles per year. If I own a car I'll drive rather than take the bus on approximately 300 local commutes (saving $1000 and 150 hours net). My time is worth $50 per hour. An alternative would be to put the $20,000 into an investment vehicle (so to speak) that would pay me 7.5% annually.
Q124. On the grid below …
Q128. Consider the act of filling up a bathtub for a baby (or yourself!). You have a faucet that you can turn more towards hot or toward cold. List out the flows, the stocks, the sources of information, the "valves," and the rules that govern the valves in this system.
Q132. Create both a causal loop and a stock and flow diagram for a thermostat, heater, and house. The house is a stock of air. When its temperature goes below some threshold, hot air is added. All along though, hot air is subtracted (or cold air is added) through leaky windows and the like. But the temperature does not change immediately upon introduction of the hot air. What are the challenges of modeling this phenomenon discretely and how can we solve them?
Q134. Consider a system for a flu vaccine clinic. People arrive at some random or fixed rate and queue up. Our first station (F) has to get them to fill out a form, sign some papers, etc. After this they get in the line for the actual shots (at station V). We have a fixed number of staff whom we will divide between the two stations, depending on the size of the queues. Draw the stock and flow diagram for the system and write the equations for Q1, Q2, F and V.
Q135. Walk us through this diagram
Q136. Write out the difference equation that represents the following scenario and the first five terms of the corresponding sequence given the stated starting value.
- Membership in a club goes up by 4 people each year. At year one it has 21 members.
- A community's population increases by 4% each year. At year one it is 350.
- A swimming pool, currently containing 100,000 gallons of water, is leaking at the rate of 2% per day but is being filled at the rate of 1,000 gallons per day.
- A retirement account which stands at $120,000 earns 3% interest annually. The owner needs to withdraw $1500 per month to pay for eldercare.
Q151. A cinema has a marquee with lots and lots of light bulbs. In any given week 1% of the light bulbs burn out. Unfortunately, between being busy and being sloppy, replacement is a little bit sporadic. Of all the bulbs that are burnt out, about 95% get replaced each week. Draw the state diagram for this system.
Q152. Translate this description into a state diagram. A population consists of people who play it safe, and daredevils. From year to year, most (97%) safe-players stay that way, but 2% turn into daredevils. About 1% of the safe-players die each year. By contrast, 10% of daredevils die each year and another 10%, seeing that, switch to playing it safe. All the other daredevils stick with the program.
Q153. A criminologist and an activist decide to collaborate on a project designed to reduce prison population. In the spirit of starting simple, they identify 4 states in which people can find themselves: never imprisoned; incarcerated; on parole; post-parole. The period of time in their analysis will be one year. Suppose 70% of the population has never been incarcerated. Each year 2% of these people are imprisoned. Of those currently incarcerated, 20% are released each year onto parole. Average parole is 5 years so that a person on parole has a 20% chance of finishing parole. Those on parole have a 10% chance of finding themselves back in prison in any given year. Individuals who are post parole have a 4% chance of returning to prison in any given year. Draw a state diagram and matrix representing this information.
Q154. Suppose a given housing market has a 10% turnover rate each year. How many houses will typically be in the first, second, third, etc. year of their mortgage at any given time? Assume 10 year mortgages to keep things simple. Draw the diagram that would be the first step in solving this problem.
Q155. Suppose 25% of the mortgages written in the first years of this century were subprime (meaning the borrowers were not very credit-worthy) and all were 5 year adjustable such that after the fifth year the monthly payments would go way up. In the market in question there is approximately 5% turnover housing each year. The housing stock in the market consists of one million units. Research has shown that 33 1/3% of subprime adjustable mortgages go into default under current conditions when they go past their five year mark (and these conditions are expected to continue for some time) when they adjust.
Q156. A state corrections system has established a new drug treatment facility for first offenders. The center has a capacity of 1000.
Q157. Sketch the transition matrix that corresponds to the following diagram
Q188. "Women's issues" have been talked about a lot in the 2012 presidential campaigns. One issue has been the hiring of women in leadership positions in society. Draw a causal loop diagram to represent the following relationships.
Q325. Have a look at the paper shown below about immunization in Uganda. Look especially at the causal loop diagrams on pages 102(146) and 103(147). Explain what is going on in each of the labeled/shaded loops. In some cases, there might be a sign missing. Based on your reading of the diagrams, supply these and explain.