Tag: Excel

Guest Post: Temperatures–A Decision Table Example

Our Guest Post today comes from Howard Weiss, Professor of Operations Management at Temple University.

I use the following example in my OM class to discuss maximin and minimax in a context the students readily understand and to demonstrate several Excel functions to my student. (It is based on a piece in Interfaces in 1990). Prior to class I search for the daily high and low temperatures in the previous month and copy them into a spreadsheet. The results appear in columns A and B.

Ultimately, I will ask my students which day was the hottest in that month and which day was the coldest. First, though, the average highs and lows in column B need to be converted to individual numbers which will be placed in columns D and E. Identifying the High temperature from column B gives me the opportunity to
• Show students Excel’s LEFT function
• Show students that the results of the LEFT function are characters, not numbers
• Show students Excel’s VALUE function to convert the characters to numerical values.
Identifying the lows is slightly more complicated due to the degree sign on the right of the values in column B which precludes us from using Excel’s RIGHT function. This gives me the opportunity to show students Excel’s MID function to pick out characters 5 and 6 from the high/low string and convert it to a numerical value.
At this point, I ask the students which date was the hottest and which was the coldest. Several use Excel’s MAX and MIN functions to find the date with the highest high temperature and lowest low temperature. Some average the high temperature and low temperature for each day and base their answer on the highest and lowest of the averages.
I then suggest that perhaps the hottest day is the day with the highest low (maximin) temperature because it is most difficult to sleep on those nights (without AC) and that the coldest day is the one with the lowest high (minimax) temperature because it is the worst day to go swimming. I also show them how to use Conditional Formatting to identify the highest and lowest temperatures in columns D and E as shown to the left.

Finally, I have the students graph (not shown) the temperatures in these two columns. It gives me the opportunity to show that it can be valuable to modify the minimum and the major units on the y-axis to make it easier to find the highs and lows.

I really like using an exercise that gives me the opportunity to display a maximin and minimax explanation and to show the students some Excel functions and features.

Guest Post: Break-even Analysis: Excel Makes Algebra Obsolete

Our Guest Post today comes from Howard Weiss, who is Professor of Operations Management at Temple University. Howard has developed both POM for Windows and Excel OM for our text.

When I began to use Excel in my classes, my main objective was to make the computations easier for the students so that we could focus on the models, inputs and outputs. At this point though, I have changed my priorities and I think it is important for us as OM (or Finance or Stat) professors to help the students develop their Excel skills as best as we can in our courses. To that end, I have taken a different approach to teaching Breakeven Analysis.

In the past, I used to develop the Break-even point algebraically just as is done in Heizer/Render/Munson and just about every other OM or business textbook. At the computer lab I would have my students enter into Excel the Fixed cost, Variable cost, Price and then the formula for the break-even point F/(P-V).

Recently, I have instead used Goal Seek, rather than the formula, to have the students find the break-even point. Instead of entering the break-even formula, I have them create a cell for the number of units, a cell for the total revenue and a cell for the total cost based on the number of units. I think expressing the total cost and total revenue in Excel helps the student to better understand these two admittedly simply concepts. I then tell the students that instead of finding the number of units where TC = TR we will create a cell for the difference between the two and use Goal Seek to search for a difference of 0 between TC and TR. The spreadsheet for Example S5 (Supp. 7) in the textbook appears as follows, along with a capture of the Goal Seek window.

I think this approach gives the student a better understanding of both break-even analysis and Goal seek.

Guest Post: Using Excel “Active Models” at St. Ambrose U.

Our Guest Post today comes from Prof. Rick Jerz at St. Ambrose University, in Davenport, Iowa. The video series he has created is terrific and we encourage you to look it over.

Many students who do not seem to like OM feel that way because they struggle with the mathematical models.  In my courses, I take a different approach.  I use the Heizer/Render text’s Excel Active Models to teach and reinforce modeling techniques and math.  Realistically, business students are typically not going to develop math models. But they might take the models and create more user-friendly ones by using a powerful business tool like Excel.  So why not introduce students to this approach in your course?

For many professors, modeling with Excel can be time demanding.  I encourage you to look at these Active Models provided by the authors. If you give them some time, you will see that they work fine in your class.

One challenge is how to teach students how to use these models.  I  solved this problem by creating my own instructional videos.  The videos give me time to teach the model and provide some tips about using Excel.  The Excel models, combined with my videos, became a great learning environment for students.  Instead of students dreading the OM course, they actually enjoy it and appreciate that they are learning more ways to use Excel creatively in business.  (See some student comments at http://www.rjerz.com/c/opsmgt/MSCI3000/Students/OM-Excel-Student_Comments.pdf)

By the way, these Active Models are “active” because they use scroll bars to quickly change data and observe a graphic dynamically changing.  This might be the best and easiest way to teach sensitivity analysis. I have found that this approach pulls together the many pieces of OM: concepts, mathematics, modeling, sensitivity analysis, and decision-making.

Here is a link to some examples of my lecture videos http://www.rjerz.com/v/rjPlayer/rjPlayer.html?crs=omexamples&vid=2&vids=1,2,3,4, as seen with my “Flash” player.  If you want to move these examples to iTunes and your iPhone/iPod/iPad, here is the feed URL (http://www.rjerz.com/c/opsmgt/Podcasts/OMU-Examples.xml)  that you should copy, then paste into iTunes (Advance|Subscribe to Podcast.)

Judge for yourself.  Watch my videos!

Guest Post: How We Use Software at Temple U.

Here is our 1st Guest Post. It comes from Prof. Howard Weiss at Temple U. As I mentioned in my Teaching Tip blog on 9/21, Howard has developed  and maintains the software that accompanies our texts. He has been on the cutting edge of using computers to teach OM for over 2 decades.

Howard Weiss writes:

When I began using software in my OM class it was Lotus 123…remember that?! I would display the spreadsheets from the front of the classroom. But on their teaching evaluations, several students requested hands-on use of software rather than just watching me. I experimented by running half of each course in the classroom and half in the public computer lab. Recall that this was at the time when few students had PCs at home. The experiment was a success, and  my departmental colleagues followed the half-time lab model. At the same time, in addition to public labs, teaching labs were being configured. Since then, roughly at the time when Windows and Excel began to become popular, all of our sections have been scheduled for half- time in the classroom and half-time in the teaching lab. We are a large school, so to make scheduling easier we have two sections of OM taught simultaneously. One section is in the classroom while the other is in the lab and vice-versa for the other lecture that week.

Changing to the alternating classroom/lab format meant a restructuring of the lectures. I try to lecture on qualitative material on the first day and then use the lab on the second day for the quantitative material rather than mixing the qualitative and quantitative material. My labs include exercises in Excel in order to build the students’ Excel skills, use of both POM for Windows and Excel OM so that the students can decide which they prefer, and use of the Active Models that accompany the Heizer/Render textbook.

Having developed POM for Windows and Excel OM, I spend a significant amount of my personal time continuously maintaining and improving these packages. I am always available to respond to any requests for help of any sort from you or your students. You can reach me at dsSoftware@prenhall.com.

 If you would like to share your teaching experiences, please just email us and we will post your Guest Blog.