Planning and Control and Pert Beta Distribution †Free Sample

Questions: Explore"Estimating With The Pert Beta Distribution". Answers: Company records show that the time taken to install a piece of equipment at customer facilities as follows: a. What is the expected time for the installation effort? Expected time for installation will be = Slowest time - Fastest time 20- 8 12 The expected time will be 12 hrs. b. What is the standard deviation associated with the installation effort? Standard deviation associated with the installation effort are as follows- = Where (20 8) / n 1 c. What is a practical interpretation for the results reported in 1a and 1b above? 1 a shows the expected hour within which the work is expected to be completed. 1 b stands for the calculation of the standard deviation. Where x is the value of the sample, is the summation and n 1 is the sample value 1. 2. Marsha is in charge of planning a large software development project. She is trying to estimate the cost of the design phase. She works with a group of five experienced designers and asks them to estimate the lowest cost, highest cost, and most typical cost possibilities. After an hour of spirited discussion, the group provides the following estimates: Lowest cost $30,000 Highest cost $50,000 Most likely cost $45,000 a. Using the PERT-Beta formula, what is the expected cost of the design effort? Pert Value (Minimum, Most likely, Maximum) Pert Value ($30000, $45000, $50000) b. What is anticipated standard deviation for the design effort? Anticipated Standard deviation = Most likely cost + highest cost lowest cost = $ 45000 + 50000-30000 = $ 45000 + 20000 = $ 75000 c. What is a practical interpretation for the results reported in 2a and 2b above? It is clear from the above that pert beta formula shows the minimum, most likely and the maximum cost of the design effort. Where standard deviation shows the deviation in the design effort. The standard deviation in the design effort is $ 75000 which is calculated in the above given manner. 3. Build-It-Quick house Construction Company has turned house-building into a science. The standard plan for framing the Excelsior Model house is to execute this effort in 10 working days. Depending on the details of site conditions, the number of carpenters needed to do the job varies slightly from job to job. as shown below: Fewest number of needed carpenters 3 Carpenters Largest number 10 Carpenters Most likely number 5 Carpenters a. Using the PERT-Beta formula, what is the expected number of needed carpenters? Expected no. of carpenters needed = (3 + 4*5 + 10)/6 = 5.5 or 6 no. of carpenters b. What is anticipated standard deviation for the number of needed carpenters? Anticipated standard deviation for no. of needed carpenters = (10 - 3)/6 = 1.17 c. What is a practical interpretation for the results reported in 3a and 3b above? The practical interpretation from the above results is that for the standard plan for framing the Excelsior Model house is to execute this effort in 10 working days, minimum 6 nos. of carpenters are required with a deviation of 1.17 no. of carpenters. 4. What are some dangers you see in relying on this estimating technique? The following are some of the dangers of relying on PERT-BETA estimating techniques: Initial estimations assumptions are not validated and thus not completely reliable and may be prone to errors. Lot of time and energy is required to draw initial assumptions numbers which make it not feasible for the management to adopt. The practical applicability of the technique is quiet debatable and many a times challenged by the scholars. It is believed by the researchers that the actual mean values calculated by this technique are often under estimated and thus may increase the risk to the management instead of reducing the risk. 5. Using your imagination and/or experience, describe another way to estimate task duration, cost, or manpower requirements The possible alternative to the estimation of task duration, cost and manpower requirements apart from PERT-BETA technique is as mentioned below: Standard-Delphi-Method: This technique is a survey technique in which the survey is guided by the monitor group and it comprises of a several rounds of surveys with group of experts. After each survey round, using statistical group judgement mean and medians of the estimates are calculated. This technique is mostly used in cases where the content of the issues are unclear and unknown. Using this technique management is able to give estimations about the study. It is more of a psychological model than of mathematical model for estimations. The use of this technique is more sensible when the management wants to assess long-term issues. 6. Note that good estimates can be made by guessing the values of only three parameters (best case, worst case, most likely case). Why is this a tremendous advantage? Good estimates can be made by guessing the values of only three parameters i.e. Best case, Worst case and most likely case. Guessing only three parameters is of tremendous advantage as it is consistent with the general psychological capability of the persons who thinks and develops any situation as a pessimistic person or optimistic person or average person thereby the people are able to align the technique with the general conditions present in the environment.