Prof. Howard Weiss – The OM Blog by Heizer, Render, & Munson

Guest Post: Safety and Government Oversight

Prof. Howard Weiss presents his monthly Guest Post today. Howard recently retired from Temple U.

Recently, we have seen three articles about the lack of safety, in different industries – food processing, shipping, and manufacturing/product design.

Fooddive.com reported that line speeds at U.S. pork plants will be slowing down after a federal judge ruled the U.S. Department of Agriculture’s removal of processing speed limits did not adequately take worker safety into consideration. The USDA is rolling back the capacity to what it had formerly been – 1,106 hogs per hour. Your Heizer/Render/Munson Capacity Management chapter (Supplement 7) notes that organizations “have found that they can operate more efficiently when their resources are not stretched to the limit.” In this case, when the capacity was increased, additional workers were not hired and the existing workers had to work faster increasing the chance of injury or pain from repetitive motions.

An earlier blog this year identified Supply Chain Risks on the High Seas. Container ships are not the only means of transportation with risks. According to Vice.com, in 2019, railroads reported 341 derailments on main line track. Of those 341 derailments, 24 were freight trains carrying 159 cars of hazardous material. While cargo loss is a concern, in the case of trains, another frightening possibility is hazardous materials leaking. Similar to hog plants, “workers have to inspect many more rail cars in a fraction of the time” than previously. Rail regulation is set by the Federal Railroad Administration.

And then, The Wall Street Journal reported that “Peloton Interactive Inc. has agreed to recall its treadmills, and its chief executive apologized for the company’s initial refusal to comply with federal safety regulators who pushed for the action weeks ago.” The Consumer Products Safety Commission has to negotiate with companies in order to release warnings about potential hazards.

Classroom discussion questions:

How has COVID affected capacity at your university or school?
What is the major advantage of shipping by rail?

Guest Post: A Tip on Teaching How to Convert Quarterly Trends to Annual Trends

Howard Weiss is Professor of Operations Management at Temple University. He has developed both POM for Windows and Excel OM for our text.

At the recent POMS conference I asked the audience: “If the quarterly trend is an increase of 100 units, then what is the annual trend?” The answer I received was, “It is so obviously 400 units year that this must be a trick question.” This is the same answer my students typically give when I ask the question.

Below is a spreadsheet displaying “perfect” data that starts at 10000 and increases at exactly 100 per quarter.

You can easily see that the annual increases are 1600 since each of the 4 quarters increases by 400 from year to year. Thus, the annual trend is 16 times the quarterly trend.

While the data above is contrived, the analysis holds for “real” data. The spreadsheet below shows the revenue at Coca-Cola (after all, the conference was in Atlanta) from 2008 to 2013.

The quarterly trend is an increase of 242 as shown in the graph, the annual trend using Excel’s SLOPE function is an increase of 3916 per year, and the ratio of the annual trend to the quarterly trend is just above 16 for this “real” data. Typically, I have my students use data from their own companies and more often than not, the ratio is near 16 for quarterly data or 144 for monthly data.

Other ideas on teaching forecasting can be found in “Let’s Put the Seasonality and Trend in Decomposition”, R. L. Nydick and H. J. Weiss.

Guest Post: Another Successful Semester with MyOMLab at Temple U.

Howard Weiss is Professor of Operations Management at Temple University. He has developed both POM for Windows and Excel OM for our text

In the past, I have guest posted about my students’ appreciation of MyOMLab– and that appreciation is even greater now! At the beginning of the semester I always ask students about any experiences they have had with the MyLabs. This semester, for the first time, well more than half the class had previously used at least one of the following; MyAccountingLab, MyMarketingLab , MyMISLab or MyStatLab. These students were already familiar with the MyOMLab structure so they could use it with no explanation. Further, about 1/4 of the students were concurrently enrolled in MyFinanceLab and MyOMLab. This makes for a single sign-on to get to both courses; and the synergy among all these labs greatly improves the students’ experiences and productivity.

Past students had commented that the exams were not like the homework in that students could not redo problems on the exams while they could on the homework. Because of their observation, for each topic this semester I gave both homework and a quiz on MyOMLab. The students very much liked having the dual assignments each week.

My courses this semester were online/hybrid courses. While using MyOMLab makes homework grading easier in face-to-face classes it is even better in online sections because it enables homework submission without the students having to send me an email with attachments as they had done in past online sections.

Even though the course is online I do give my exams face-to-face. From the onset of my usage of MyOMLab the students have very much liked getting the exam results immediately after completing the exam. My better students review their exams after getting the grade and ask me questions about their mistakes. This seldom happened when I gave final exams because the students never saw their graded exams. Reviewing the exam makes for a great learning experience. After all, one of the best ways to learn is from our mistakes.

Guest Post: Custom Teaching Evaluations at Temple University

Our Guest Post today comes from Prof. Howard Weiss. Howard has developed both POM for Windows and Excel OM, which we provide free with our OM texts.

At Temple U., as at most colleges, we have long distributed course evaluations to students at the end of the semester. These evaluations include general questions about the quality of the instructor, the value of the course, the workload in the course and include opportunities for students to provide general comments. There are two glaring difficulties with these evaluations. Possibly due to Temple’s size, the results are not presented back to the faculty members until after the start of the spring semester. This makes it difficult to make adjustments in time for the spring semester based on fall results. More recently, a new difficulty has arisen. The university evaluations are performed on the web, and the response rate has dropped greatly.

For some time now, I have been giving my students my own evaluation, with questions that are much more specific than those on the university forms. I ask them about the course requirements and the weights that they think should be assigned to each requirement. I ask about the use of Excel in the classroom. I allow my students to use either POM for Windows, Excel OM, or both for homework and exams, and I ask them if I should continue to do so or require only one of the 2 packages. I ask about the value of preparing their presentations for my class, the value of actually presenting and the value of listening to classmates’ presentations.

Of course, I also ask about the use of MyOMLab in the class. Once again this fall, the students have overwhelmingly endorsed MyOMLab. 100% of students who responded to my survey agreed that MyOMLab should continue to be used for homework and quizzes. And 84% wrote that I should continue to use MyOMLab for the exams. These results are very consistent with surveys from previous years.

I like having my own survey with specific feedback and receiving the feedback in time to prepare for the next semester. Do you agree?

Guest Post: Celebrating 25 Years of POM Software

Our Guest Post today comes from Prof. Howard Weiss, at Temple University. Howard writes about his 25 years of developing POM for Windows, which we provide free with our OM texts.

This month marks the 25^th anniversary of Pearson’s POM software package. Just as technology has evolved over the past 25 years, so too, has this educational resource. The initial package, PC-POM, indicated that POM was designed for DOS and would not run on a Mac computer. Today, POM will work well on a Mac using vmWare or Parallels to emulate Windows.

Jay and Barry decided that PC:POM would be a valuable addition to their text and it became available as AB:POM, where AB stood for our publisher at that time, Allyn & Bacon. The POM software has been distributed with every edition of Heizer/Render since its inception. (By the way, OR/MS Today (page 10) just interviewed Jay and Barry about their 30+ years of writing).

In 1996, with the rising popularity of Windows, POM was redeveloped for Windows. While the solution techniques remained the same, it was a monumental challenge to change the graphical user interface to match the look and feel of Windows. Cutting and pasting between POM and other Windows programs such as Excel and Word were built into POM. For preparing the manual, scissors and paste were no longer necessary, because screen captures could be copied from POM and pasted into Word. In addition an option to save problems as Excel files was built into POM in which the models are saved as complete Excel models with appropriate formulas and/or graphs.

An exciting recent addition (in Version 4) is the capability to copy from MyOMLab and paste into POM.

Developing the software has been a rewarding venture and it has been very gratifying to hear from students around the world who have used the program. I hope that if you use POM, you and your students have had the same positive experiences. I encourage those of you who have not used it to give it a try in your classroom.

Guest Post: Another Approach to Teaching the Center-of-Gravity Model

Our Guest Post today comes from Prof. Howard Weiss, at Temple University. Howard is the developer of the POM for Windows and Excel OM problem solving software that we provide free with our OM texts.

Your Heizer/Render textbook covers the Center-of-Gravity Method in Chapter 8. However, there is a related model that is not covered and is easy to explain to the students. Consider Example 3 in the text, on page 322, in which Quain’s Discount Department Stores is looking for a location to build a new warehouse. Suppose though that rather than seeking a “central” location, the warehouse must be built in one of the four cities that currently has a store – Chicago, Pittsburgh, New York or Atlanta.

This revised example can lead to the discussion of straight-line (Euclidean) distance as compared with city-block/taxi distance and can serve as a student reminder about the Pythagorean Theorem. The distance computations are tedious but not difficult. Of course, using POM for Windows (shown below)

or Excel OM (below) the students can easily identify that Pittsburgh is the city with the least total weighted movement from each of the other 3 cities with a total weighted movement of 318,692.

Guest Post: Jazzing Up Your OM Syllabus

When I began teaching in 1975 I would write my syllabus by hand and my secretary would type it on mimeograph paper for duplication and distribution to students. The mimeograph morphed to Xerox, and in the 1980s I began to type my own syllabus using my PC. When the internet became available I stopped reproducing the syllabus and had the students download it for themselves. I kept the syllabus black and white since many students did not have a color printer.

At this point, color printing is available to all of my students, either at home or in our computer labs. This allows me to include graphics (eg, Labor day, Halloween) on my syllabus in order to make it more engaging.

wordle More recently I have begun to add a word cloud to my syllabus. A word cloud is a visual representation of the content of a document or web site. The size of the font of the words in the word cloud is proportional to the number of times the word appears in the document or web site. This enables viewers to very easily pick out the more important terms and concepts in the document.

Wordle.net is a web site that enables users to very easily create their own Word clouds. I have taken my course syllabus, modified it some, and used wordle.net to create the word cloud (shown here) that I have included on my syllabus. Wordle gives the user the opportunity to customize the cloud by selecting the font, the colors, the layout (horizontal, vertical, mixed), and the maximum number of words in the cloud. The word cloud improves the appearance of my syllabus and it gives a sign to the students that I am current in that I use the recently developed word cloud representation.

Another use: When a colleague retired recently, we took his resume, imported it into Wordle and gave him an 18” by 24” framed picture of his resume’s word cloud–a very unique, highly appreciated gift.

Guest Post: How I Teach Forecasting at Temple U.

Professor Howard Weiss at Temple University’s Fox School of Business writes about how he uses software to teach forecasting. Howard, the developer of both Excel OM and POM for Windows, is also Academic Director of Temple’s EMBA program.

For several years, I have been assigning my students a forecasting project using data from their company. Since I want students to learn about seasonality, I require the data must be four complete cycles of the measurement. That is, I ask for 48 months, 16 quarters, 20 or 28 days, or 8 or 24 hours over 4 days. Most students are able to obtain data from their company and for those who cannot I ask them to find acceptable data on the web or ask a classmate for data.

I have the students first present three graphs: a graph of the data over 48 months, a graph of the annual data over the 4 years, and a stacked graph of the data over 12 months for each of the 4 years. For the first two graphs, I have them apply Excel’s easy-to-use option to identify the trend line. I also ask the students to identify the ratio of the trends. They expect annual to monthly trend to be near 12, and are surprised when it is closer to 144. I have the students use the stacked graph to identify seasonality.

I then require the students to run their data through most of the models in the Heizer-Render textbook. Using POM for Windows (which comes free with the book), it is very easy to change from model to model, to determine the best n for moving averages and the best alpha for exponential smoothing. It also is straightforward to run the decomposition methods that are in POM, which will determine seasonal factors as in the textbook. For each model, students are to identify the bias, MAD, MSE, standard error, and MAPE –and select the best forecasting method based on the error measures. Finally, using the method they have selected, I ask them to identify forecasts for the next 12 months and the seasonal factors for each month.

The students very much like applying forecasting to data from their own company. They also appreciate the value of the graphs, the ease in changing from one method to another in POM, and that the different methods will yield different results.

Guest Post: The Numbers Don’t Lie

Professor Howard Weiss at Temple University’s Fox School of Business writes about his experiences with MyOMLab. Howard, the developer of both Excel OM and POM for Windows, is also Academic Director of Temple’s EMBA program.

I just received my teaching evaluation scores from the Fall 2011 semester and once again they have improved. I have evaluations that go back to 2005, but Temple U. changed evaluation questions beginning in 2008 so I can only compare evaluations from 2008 and later. Fall of 2008 was the last year that I taught the course without MyOMLab. The two questions that we consider the most important are:

The instructor taught this course well
I learned a great deal in this course.

My average score in 2008 on the first question above was 4.15. The average during my last 3 MyOMLab years is 4.43. On the second question, I have seen a steady increase. Before using MyOMLab the average was 3.95. Since 2009, the averages have risen each year from 4.1 to 4.3 to 4.4 this past Fall. Since the only change in the course has been my adoption of MyOMLab, I have to believe that use of MyOMLab is a major reason for the increase.

On the evaluations, several students write: “ MyOMLab was very helpful” or “MyOMLab contributes to my learning”. From discussions, it is clear that they write this because MyOMLab offers instant help when doing homework problems. They appreciate the feedback they receive when they enter an incorrect answer, and also the Help Me Solve This Option, which breaks down the problem step-by-step. They value the eText option which takes them directly to the right pages in the textbook. They don’t have to carry their textbook around, nor do they have to page through the textbook to find the relevant information. Of course, when they are stuck on a problem, they like the Ask My Instructor option and my responsiveness to their questions sent to me from MyOMLab. (I appreciate that the homework problem from MyOMLab is included in the email I am sent.)

The only negative comment on the evaluations was in 2009, and was about MyOMLab having little tolerance for round off errors. This has been corrected and is no longer an issue. My hope is that MyOMLab will get even better and that my evaluation scores will also!

Guest Post: Using MyOMLab for Exams at Temple University

Today’s Guest Post comes from Professor Howard Weiss at Temple University’s Fox School of Business. Howard, the developer of both Excel OM and POM for Windows, is also Director of Temple’s EMBA program.

When myomlab first became available in the Fall of 2009 I had some qualms about using it for my exams because it was new technology and I was worried that there might be technical problems. On my midterm exam, I gave my usual paper exam except that I put one question on myomlab in order to see how the process worked. It worked flawlessly. Even when one or two students had some issue in the middle of the exam, the exam reopened at the same point where it closed. For my final exam I gave half of the problems on paper exams and half on myomlab. The students loved getting their myomlab grade immediately. Of course, I loved not having to grade those exams and I also loved that students had different data from each other for the same problems.

When I surveyed my students they requested that the entire exam should be from myomlab. I am not sure how much of their opinion was positive towards myomlab and how much was negative towards my own questions but I certainly had no reservations about accommodating the students. Since that first semester I have used myomlab exclusively for my undergraduate exams. It is even nicer to use myomlab now than when it first came out because it now has a feature that allows me to enter my own problems or questions into the exam.

There can be one downside to using myomlab. Myomlab does not give partial credit in the way a professor would. For example, on my written exams, if a student entered a wrong demand rate in an inventory model but otherwise interpreted the results properly I would give half credit even though all of the answers would be wrong. In myomlab, the student gets no credit. Of course, I have warned my students about this and told them they need to be extra careful when using myomlab just like they need to be extra careful when filing a tax return. Myomlab is as unforgiving as the IRS when mistakes are made!

Guest Post: Great Homework Problems for Software

Today’s guest post is by Prof. Howard Weiss at the Fox School of Business, Temple University. Howard is also Director of the Fox EMBA program. You can view Howard’s syllabus by clicking here.

As the developer of POM for Windows and Excel OM, I am naturally biased about the use of software in an OM class. I believe that students should not be bogged down in the mechanics of computations but rather should understand concepts, inputs and outputs. While 90% of the homework problems in the Heizer/Render text can be solved with my two programs, I see four types of categories of problems that are strong candidates for assigning students using the software.

(1) Large problems, such as project management are good example of models with simple but tedious computations. There is no reason to ask students to solve CPM models with more than 8 activities by hand. In forecasting, I want students to understand the meaning and use of the trend and the error measures rather than spending time computing the intercept and slope. For control charts, if a student has computed results for 5 samples by hand or with Excel does it really make sense to ask the student to calculate the results by hand for 30 samples?

(2) Iterative Models, such as LP, assignment, and transportation, should focus on the formulation of the problems and the interpretation of the results.

(3) Models with multiple methods, where it is useful for students to compare the results of these different methods without having to try every method by hand themselves. Models that come to mind are time-series analysis, assembly line balancing and one-machine scheduling. In addition, it is much easier to change the number of servers in a waiting line model in POM or Excel OM than by hand.

(4) Models for which the software goes a step further than the text, such as: machine scheduling, where Moore’s method is available to minimize the number of late jobs; Wagner-Whitin for lot-sizing; LP for a ranging analysis.

Guest Post: Why Our Students Love MyOMLab at Temple University

Today’s Guest Blog is from Professor Howard Weiss at Temple University’s Fox School of Business and Management. Dr. Weiss is the developer of both POM for Windows and Excel OM, the two problem-solving software packages available free to adopters of our OM texts.

I started using myomlab when it first came out in Fall of 2009. In spite of a few difficulties that occurred with the automated grading that first semester, my students loved myomlab. This past semester has gone even better for my students due to the Copy feature that has been added to myomlab and the Paste from myomlab feature that has been added to POM for Windows and Excel OM. These features enable students to copy data from problems where the data is expressed in table form. The table of data can be copied from myomlab and then pasted into Excel and then manipulated or pasted directly into either a model created in POM for Windows or a model generated by Excel OM.

The advantages are obvious. Students do not waste their time entering data but rather use the time obtaining and interpreting results. Essentially, my students this year spent less time on homework assignments than my students from last year and also had more time to think about the problems during the exams since they spent less time entering data. In addition, the automated copy of data from myomlab eliminates the possibility that the student will get a problem wrong due to a data entry error. Sadly, students still get problems wrong in other ways, such as by using the wrong model, selecting the wrong method or choosing the wrong output value as their answer but they won’t get a problem wrong by mistyping a number.

I always give my own course evaluation at the end of each semester where I ask students for feedback about the specifics of the course rather than the general feedback that is asked of students by Temple University. Once again, each and every student indicated that I should continue to use myomlab. The best comment was, “That is amazing! I was able to copy the data set right into POM and I solved the problem.”