I started this channel to give tips to my yearly cohort of about 1,400 students on statistical calculations, and calculator usage. A lot of those videos were essential knowledge but yet found little time to be covered in class. Gradually, I've expanded it to include full-fledged university-level course discussions and related software usage. Most of the videos done here are used by year one or freshmen students in university.
Many students commented my seminars are easy to understand even for tougher topics, but also intense at the same time! I do appreciate that some topics are just hard to understand with one pass of discussion. So having a channel to keep the videos certainly would help to repeat the essential portions for different students.
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Hi, thanks for your question. I suppose you meant Vehicle Routing Problem (VRP)? No, not exactly. In shortest route problem (SRP), the problem definition is with one start point (A) and one end point (not the same as start point) (B), and the output is to give a connected sequence of paths to take so that a "vehicle" or person could travel from A to B in the lowest possible total cost (whether it is travel fee, fuel charges, time, labor hours, etc). Traveling Salesman Problem (TSP) starts with a given number of places (nodes) and known paths connecting the places (the routes), and a starting node A. The required output is to provide a connected path so that ONE "vehicle" or person could travel from A, touches all nodes, and then back to A in a manner that incurs the lowest possible total cost. VRP generalizes TSP by allowing for more than one "vehicle" or person to accomplish the task of visiting all nodes such that they collectively touch all nodes once and only once (except A), and all vehicles return back to A. This problem is getting more common these days as ecommerce and online purchases requiring fleet deliveries flourish. So in short, VRP is not exactly achieving the same objectives as SRP. Both have their important uses and applications.
Good question. I suppose by "manually" you meant by hand calculations possibly assisted by a desktop calculator? If so, in very simple cases, like 1 or 2 variables with 1 to 2 constraints, you could possibly use graphical methods to deduce them quite readily. Unfortunately, such solutions are also often trivial and uninteresting. For larger number of variables and more constraints, it would become very tough to do by hand, so much so that it would just be easier to use ready software (eg Excel solver) and "manually" set up Excel solver to generate the sensitivity report.
Can believe i have a test yesterday and I got similar problem to solve. I miss to find your channel earlier. A least from now on I have a good source of information like your channel. Thank you. By the way, what book would you suggest to use for Management decisión with mathematic and linear programing problems.
Thanks for your sharing. Just wondering if the reduced cost is positive, from your explanation, the formula should be OFC - (reduced cost). But in the case of profit maximization problem, if the coef. is reduced according to that formula, will we still be able to increase our profit? Or we should actually increase the OFC? Your response will be greatly appreciated!
Thank you so much professor. I watched a ton of your videos. You are really good at teaching. Your explanations are so clear and concise. Couldn't thank you enough!
Hi, for the Westwood Plant 1 coefficient, should it be 30, as $30 is the transportation cost? I think the objective function in the slides is incorrect.
Hello, thank you for the explanation! I have a question, how can we turn the Reduced Cost negative if we are trying to see at what point we a variable should be removed? thank you!
I assume you're asking about why for EVSI we add back the cost that was charged by the consultant? If so, that's because we often like to compare EVSI with EVPI. EVPI is more a perfectionist measure and doesn't come with any cost (as no consultant can ever achieve EVwPI). Thus, to be comparable, EVSI shouldn't come with arbitrary cost (in the form of fees) charged by the consultant. Hope this clarifies.
