Midterm Quiz 2 - GT Students and Verified MM Learners Midterm Quiz 2 ISYE6501x Courseware edX (answered)
4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Course Midter… Midter… Midter… Midterm Quiz 2 - GT Students and VeriÕed MM Learners 90 Minute Time Limit Instructions Work alone. Do not collaborate with or copy from anyone else. You may use any of the following resources: One sheet (both sides) of handwritten (not photocopied or scanned) notes If any question seems ambiguous, use the most reasonable interpretation (i.e. don't be like Calvin): Good Luck! This the beginning of Midterm Quiz 2. Please make sure that you submit all your answers before the time runs out. Once you submit an answer to a question, you cannot change it. There is no overall Submit button. 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Answers are displayed within the problem Information for Question 1 There are Õve questions labeled "Question 1." Answer all Õve questions. For each of the following Õve questions, select the probability distribution that could best be used to model the described scenario. Each distribution might be used, zero, one, or more than one time in the Õve questions. Question 1 0.0/1.4 points (graded) Time between people clicking an online banner ad Weibull Answer: Exponential You have used 1 of 1 attempt Question 1 0.0/1.4 points (graded) Number of people clicking an online banner ad each hour Exponential Answer: Poisson You have used 1 of 1 attempt Question 1 0.0/1.4 points (graded) Time from when a house is put on the market until the Õrst oàer is received Poisson Answer: Weibull Submit Submit 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Answers are displayed within the problem Answers are displayed within the problem You have used 1 of 1 attempt Question 1 0.0/1.4 points (graded) Number of hits to a real estate web site each minute Binomial Answer: Poisson You have used 1 of 1 attempt Question 1 0.0/1.4 points (graded) Time from the start of a World Cup soccer match until a goal is scored Poisson Answer: Weibull You have used 1 of 1 attempt Questions 2a, 2b 5.0/10.0 points (graded) Five classiÕcation models were built for predicting whether a neighborhood will soon see a large rise in home prices, based on public elementary school ratings and other factors. The training data set was missing the school rating variable for every new school (3% of the data points). Submit Submit Submit 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Because ratings are unavailable for newly-opened schools, it is believed that locations that have recently experienced high population growth are more likely to have missing school rating data. Model 1 used imputation, Õlling in the missing data with the average school rating from the rest of the data. Model 2 used imputation, building a regression model to Õll in the missing school rating data based on other variables. Model 3 used imputation, Õrst building a classiÕcation model to estimate (based on other variables) whether a new school is likely to have been built as a result of recent population growth (or whether it has been built for another purpose, e.g. to replace a very old school), and then using that classiÕcation to select one of two regression models to Õll in an estimate of the school rating; there are two diàerent regression models (based on other variables), one for neighborhoods with new schools built due to population growth, and one for neighborhoods with new schools built for other reasons. Model 4 used a binary variable to identify locations with missing information. Model 5 used a categorical variable: Õrst, a classiÕcation model was used to estimate whether a new school is likely to have been built as a result of recent population growth; and then each neighborhood was categorized as "data available", "missing, population growth", or "missing, other reason". a. If school ratings cannot be reasonably well-predicted from the other factors, and new schools built due to recent population growth can be reasonably well-classiÕed using the other factors, which model would you recommend? Model 1 Model 2 Model 3 Model 4 Model 5 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem b. In which of the following situations would you recommend using Model 2? [All predictions and classiÕcations below are using the other factors.] You have used 1 of 1 attempt Information for Question 3 In a diet problem (like we saw in the lessons and homework), let x be the amount of food i in the solution (x >= 0), and let M be the maximum amount that can be eaten of any food. Suppose we added new variables y that are binary (i.e., they must be either 0 or 1): if food i is eaten in the solution, then it is part of the solution (y = 1); otherwise y = 0. There are Õve questions labeled "Question 3." Answer all Õve questions. For each of the following Õve questions, select the mathematical constraint that best corresponds to the English sentence. Each constraint might be used, zero, one, or more than one time in the Õve questions. Question 3 Ratings can be well-predicted, and reasons for building schools can be well-classiÕed. Ratings can be well-predicted, and reasons for building schools cannot be wellclassiÕed. Ratings cannot be well-predicted, and reasons for building schools can be wellclassiÕed. Ratings cannot be well-predicted, and reasons for building schools cannot be wellclassiÕed. Submit i i i i i4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem 1.4/1.4 points (graded) Select the mathematical constraint that corresponds to the following English sentence: No more than two of broccoli, cheese sauce, and peanut butter may be eaten. You have used 1 of 1 attempt Question 3 1.4/1.4 points (graded) Select the mathematical constraint that corresponds to the following English sentence: ypeanutbutter + ycheesesauce = 0 ypeanutbutter = 1 − ycheesesauce ybroccoli ≤ ycheesesauce + ypeanutbutter ybroccoli + ycheesesauce + ypeanutbutter ≤ 2 xcheesesauce ≤ Mycheesesauce ycheesesauce = 1 xbroccoli ≤ Mypeanutbutter xbroccoli ≥ Mypeanutbutter Submit 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem If any amount of broccoli is eaten, then peanut butter must also be eaten. You have used 1 of 1 attempt Question 3 1.4/1.4 points (graded) Select the mathematical constraint that corresponds to the following English sentence: Neither peanut butter nor cheese sauce can be eaten. ypeanutbutter + ycheesesauce = 0 ypeanutbutter = 1 − ycheesesauce ybroccoli ≤ ycheesesauce + ypeanutbutter ybroccoli + ycheesesauce + ypeanutbutter ≤ 2 xcheesesauce ≤ Mycheesesauce ycheesesauce = 1 xbroccoli ≤ Mypeanutbutter xbroccoli ≥ Mypeanutbutter Submit ypeanutbutter + ycheesesauce = 0 ypeanutbutter = 1 − ycheesesauce4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem You have used 1 of 1 attempt Question 3 1.4/1.4 points (graded) Select the mathematical constraint that corresponds to the following English sentence: Either cheese sauce or peanut butter (or both) must be eaten with broccoli. ybroccoli ≤ ycheesesauce + ypeanutbutter ybroccoli + ycheesesauce + ypeanutbutter ≤ 2 xcheesesauce ≤ Mycheesesauce ycheesesauce = 1 xbroccoli ≤ Mypeanutbutter xbroccoli ≥ Mypeanutbutter Submit ypeanutbutter + ycheesesauce = 0 ypeanutbutter = 1 − ycheesesauce ybroccoli ≤ ycheesesauce + ypeanutbutter ybroccoli + ycheesesauce + ypeanutbutter ≤ 24/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem You have used 1 of 1 attempt Question 3 1.4/1.4 points (graded) Select the mathematical constraint that corresponds to the following English sentence: Broccoli can only be eaten if either cheese sauce or peanut butter (or both) is also eaten. xcheesesauce ≤ Mycheesesauce ycheesesauce = 1 xbroccoli ≤ Mypeanutbutter xbroccoli ≥ Mypeanutbutter Submit ypeanutbutter + ycheesesauce = 0 ypeanutbutter = 1 − ycheesesauce ybroccoli ≤ ycheesesauce + ypeanutbutter ybroccoli + ycheesesauce + ypeanutbutter ≤ 2 xcheesesauce ≤ Mycheesesauce ycheesesauce = 14/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem You have used 1 of 1 attempt Question 4a 5.0/5.0 points (graded) A large company's internal IT helpdesk has created a stochastic discrete-event simulation model of its operations, including help-request arrivals, routing of requests to the appropriate staà member, and the amount of time needed to give assistance. The helpdesk is not Õrst-come-Õrst-served. A more-important problem (like the spread of serious malware to many company computers) will be dealt with ahead of a less-important problem (like a ripped mouse pad), and a higher-level employee (like the CEO) might be helped ahead of a lower-level employee (like a worker in the mailroom). When a new request for help comes in, the helpdesk will run the simulation to quickly give the requester an estimate of the expected wait time before being helped. How many times does the company need to run the simulation for each new help request (i.e., how many replications are needed)? You have used 1 of 1 attempt xbroccoli ≤ Mypeanutbutter xbroccoli ≥ Mypeanutbutter Submit Once, because the outcome will be the same each time Many times, because of the variability and randomness Once, because each patient is unique Submit4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Information for Question 4b The Õgure above shows the average of the Õrst x simulated wait times, as new replications ("runs") are run and added into the overall average. It is not showing the wait time just for each replication. For example, after x=101 replications, the wait time of the 101st replication is not necessarily 72, but the average of those 101 replications is about 72. Question 4b 4.0/5.0 points (graded) If the goal is to report the expected wait time to within +/- 2 minutes, what can you conclude from the Õgure above? Select all of the answers that are correct. The simulation could have been stopped after 400 runs (replications). 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Answers are displayed within the problem You have used 1 of 1 attempt Question 4c 6.0/6.0 points (graded) Suppose it is discovered that simulated wait times are 50% higher than actual wait times, on average. What would you recommend that they do? You have used 1 of 1 attempt The simulation could even have been stopped after 300 runs (replications). The simulated wait time was 50 or less at least once out of all the runs (replications). The expected wait time of simulated runs (replications) is likely to be between 65 and 75. There is signiÕcant variability in the simulated wait time of the runs (replications). Submit Scale down all estimates by a factor of 1/1.50 to get the average simulation estimates to match the average actual wait times. Investigate to see what's wrong with the simulation, because it's a poor match to reality. Use the 50%-higher estimates, because that's what the simulation output is. Submit 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Information for Question 5 For each of the optimization problems below, select its most precise classiÕcation. In each model, x are the variables, all other letters (a,b,c) refer to known data, and the values of c are all positive. There are seven questions labeled "Question 5". Answer all seven questions. Each classiÕcation might be used, zero, one, or more than one time in the seven questions. Question 5 0.0/1.0 point (graded) Minimize subject to for all all Convex program Answer: General non-convex program You have used 1 of 1 attempt Question 5 1.0/1.0 point (graded) Minimize subject to for all all Convex quadratic program Answer: Convex quadratic program You have used 1 of 1 attempt ∑i cixi ∑i ∑k aikjxixk ≥ bj j xi ≥ 0 Submit ∑i cix2 i ∑i aijxi ≥ bj j xi ≥ 04/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Answers are displayed within the problem Answers are displayed within the problem Question 5 1.0/1.0 point (graded) Minimize subject to for all all Linear program Answer: Linear program You have used 1 of 1 attempt Question 5 0.0/1.0 point (graded) Minimize subject to for all all Convex quadratic program Answer: Convex program You have used 1 of 1 attempt Submit ∑i cixi ∑i aijxi ≥ bj j xi ≥ 0 Submit ∑i ci|xi − 6| ∑i aijxi ≥ bj j xi ≥ 0 Submit 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Answers are displayed within the problem Question 5 1.0/1.0 point (graded) Minimize sin subject to for all all General non-convex program Answer: General non-convex program You have used 1 of 1 attempt Question 5 1.0/1.0 point (graded) Minimize subject to for all all Integer program Answer: Integer program You have used 1 of 1 attempt Question 5 1.0/1.0 point (graded) Minimize log subject to for all all ∑i ci xi ∑i aijxi ≥ bj j xi ≥ 0 Submit ∑i cixi ∑i aijxi ≥ bj j xi ∈ {0, 1} Submit ∑i( ci)xi ∑i aijxi ≥ bj j xi ≥ 04/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Linear program Answer: Linear program You have used 1 of 1 attempt Questions 6a,6b,6c 9.32/12.0 points (graded) A medium-sized city is analyzing the size of its judicial system, speciÕcally the number of judges it has available for hearing cases at diàerent times of the year. At busy times (about 10% of the times), the arrival rate is 20 new cases ready for trial per day. At other times, the arrival rate is 10 new cases ready for trial per day. Once an judge is assigned to a case (at any time), it takes an average of 0.5 days to complete. [NOTE: This is a very simpliÕed version of the judicial system. If you have deeper knowledge of how the judicial system works, please do not use it for this question; you would end up making the question more complex than it is designed to be.] a. The Õrst model the city tries is a queuing model with 3 judges always available. What would you expect the queuing model to show? Submit Wait times are low at both busy and non-busy times. Wait times are low at busy times and high at non-busy times. Wait times are low at non-busy times and high at busy times. Wait times are high at both busy and non-busy times.4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX b. The second model the city tries is a queuing model with 15 judges available during busy times and 7 judges availableduring non-busy times. What would you expect the queuing model to show? c. The third model the city tries is a Markov chain, where each state is the number of cases waiitng (e.g., 0 cases waiting, 1 case waiting, etc.). When there are at least 20 total cases waiting, the city will refer waiting caess to arbitrators who try to get the cases settled without a trial (arbitration also takes about 0.5 days per case). Once the arbitrators start hearing cases, the arbitrators continue to be assigned cases until no more cases are waiting. Select all of the following statements about the model and the memoryless property (previous states don't aàect the probability of moving from one state to another) that are true. You have used 1 of 1 attempt Wait times are low at both busy and non-busy times. Wait times are low at busy times and high at non-busy times. Wait times are low at non-busy times and high at busy times. Wait times are high at both busy and non-busy times. The process is memoryless. If the arrivals follow the Poisson distribution and the checkout times follow the Exponential distribution, then the process is memoryless. We can't say the process is memoryless because the model is not well-deÕned. For example, the transition probabilities from the state "3 people are waiting" depend on how many lines are currently open, which isn't captured as part of the states of the Markov chain. Submit4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Questions 7a,7b 0.0/10.0 points (graded) A charity is testing two diàerent mailings to see whether one generates more donations than another. The charity is using A/B testing: For each person on the charity's mailing list, the charity randomly selects one mailing or the other to send. The results after 2000 trials are shown below. Trials Donation rate 95% conÕdence interval Option A 1036 4.8% 3.6%-6.2% Option B 964 10.4% 8.5%-12.3% Note: Higher donation rates are better. a. What should the retailer do? Later, the charity developed 7 new options, so they used a multi-armed bandit approach where each option is chosen with probability proportional to its likelihood of being the best. The results after 2000 total trials are shown below. Donation rate 95% conÕdence interval Option #1 4.0% 0.8%-7.9% Option #2 5.4% 2.4%-9.0% Option #3 6.6% 3.3%-9.9% Option #4 8.0% 5.0%-11.5% Option #5 10.6% 7.3%-13.8% Option #6 12.9% 9.7%-16.3% Switch to exploitation (utilize Option A only; A is clearly better) Switch to exploitation (utilize Option B only; B is clearly better) More exploration (test both options; it is unclear yet which is better)4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Donation rate 95% conÕdence interval Option #7 15.0% 11.9%-18.3% Note: Higher donation rates are better. b. What should the retailer do? You have used 1 of 1 attempt Information for Question 8a For each of the mathematical optimization models, select the variableselection/regularization method it most-precisely represents (or select "none of the above" if none of the other choices are appropriate). In each model, x is the data, y is the response, a are the coeÞcients, n is the number of data points, m is the number of predictors, and T and are appropriate constants. There are four questions labeled "Question 8a". Answer all four questions. Each of the choices might be used zero, one, or more than one time in the four questions. Question 8a Move to pure exploitation: use only Option 7 Continue the multi-armed bandit approach using only Options 6 and 7 Continue the multi-armed bandit approach using only Options 5, 6, and 7 Continue the multi-armed bandit approach using all seven options Submit λ4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Answers are displayed within the problem 1.0/1.0 point (graded) Minimize subject to Lasso regression Answer: Lasso regression You have used 1 of 1 attempt Question 8a 1.0/1.0 point (graded) Minimize subject to Elastic net Answer: Elastic net You have used 1 of 1 attempt Question 8a 1.0/1.0 point (graded) Minimize subject to Ridge regression Answer: Ridge regression You have used 1 of 1 attempt ∑n i=1 (yi − (a0 + ∑m j=1 ajxij))2 ∑m j=1 |aj| ≤ T Submit ∑n i=1 (yi − (a0 + ∑m j=1 ajxij))2 λ∑m j=1 |aj| + (1 − λ)∑m j=1 (aj)2 ≤ T Submit ∑n i=1 (yi − (a0 + ∑m j=1 ajxij))2 ∑m j=1 (aj)2 ≤ T Submit4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Answers are displayed within the problem Question 8a 1.0/1.0 point (graded) Minimize None of the above Answer: None of the above You have used 1 of 1 attempt ∑n i=1 (yi − (a0 + ∑m j=1 ajxij))2 Submit Question 8b 2/4 points (graded) Keyboard Help Rank the following regression and variable-selection/regularization methods from fewest variables selected to most variables selected. All four methods will be used (the bottom contains two equivalent spaces). Lasso regression4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Question 8c 6.0/6.0 points (graded) FEEDBACK Correctly placed 2 items. Misplaced 2 items. Good work! You have completed this drag and drop problem. Final attempt was used, highest score is 2.0 Submit You have used 1 of 1 attempts. Reset Show Answer Elastic net Ridge regression Linear regression4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Select all of the following reasons that you might want to use stepwise regression, lasso, etc. to limit the number of factors in a model. You have used 1 of 1 attempt Question 8d 3.0/3.0 points (graded) In the simple linear regression model i. What are the variables from an optimization perspective? To Õnd a more-complex model To Õnd a simpler model Because there isn't enough data to avoid overÕtting a model with many factors Submit minimize∑ i=1 n (yi − (a0 +∑ )) j=1 m ajxij 2 Only xij Both xij and aj Both xij and yi Only aj Only yi4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem ii. What are the variables from a regression perspective? You have used 1 of 1 attempt Only yi Both xij and aj Only aj Only xij Both xij and yi Submit Question 8e 3/7 points (graded) Keyboard Help Put the following seven steps in order, from what is done Õrst to what is done last.4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX FEEDBACK Correctly placed 3 items. Misplaced 4 items. Good work! You have completed this drag and drop problem. Final attempt was used, highest score is 3.0 Submit You have used 1 of 1 attempts. Reset Show Answer Remove outliers Impute missing data values Scale data Fit lasso regression model on all variables Fit linear regression, regression tree, and random forest models using variables chosen by lasso regression Pick model to use based on performance on a diàerent data set Test model on another diàerent set of data to estimate quality4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX Answers are displayed within the problem Answers are displayed within the problem There are Õve questions labeled "Question 9". Answer all Õve questions. For each question, select the most appropriate model/approach to answer the question/analyze the situation described. Each model/approach might be used zero, one, or more than one time in the Õve questions. Question 9 1.4/1.4 points (graded) Nobody knows exactly how investments will change in value. What's the best set to invest in? Stochastic optimization Answer: Stochastic optimization You have used 1 of 1 attempt Question 9 1.4/1.4 points (graded) In the MS Analytics program, which groups of electives are often taken by the same students? Louvain algorithm Answer: Louvain algorithm You have used 1 of 1 attempt Question 9 0.0/1.4 points (graded) Is the median home price in Atlanta signiÕcantly lower than the median home price in Boston? Game theoretic analysis Answer: Non-parametric test Submit Submit 4/6/2020 Midterm Quiz 2 - GT Students and Verified MM Learners | Midterm Quiz 2 | ISYE6501x Courseware | edX © All Rights Reserved Answers are displayed within the problem Answers are displayed within the problem Answers are displayed within the problem You have used 1 of 1 attempt Question 9 1.4/1.4 points (graded) Does Lasik surgery signiÕcantly improve the median vision of people who get that surgery? Non-parametric test Answer: Non-parametric test You have used 1 of 1 attempt Question 9 0.0/1.4 points (graded) Find the best airline Öight schedule given uncertain weather-related delays and maintenance delays. Queuing Answer: Stochastic optimization You have used 1 of 1 attempt This the end of Midterm Quiz 2. Please make sure that you submit all your answers before the time runs out. There is no overall Submit button. Submit Submit Submit
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midterm quiz 2 gt students and verified mm learners
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midterm quiz 2 isye6501x courseware edx
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there are Õve questions labeled question 1 answer all Õve questions for each of t
