One more educational update on my blog. This time, it is the interpretation of exam in microeconomics, which took place on February 1st, 2019, in two distinct majors of studies, i.e. International Relations, and Management. First, right below, I am presenting the contents of the exam sheet, such as it was distributed to students. Then, further below, I develop an interpretation of possible answers to the questions asked. One preliminary remark is due: the entire exam refers to Tesla Inc. as business case. In my classes of Microeconomics, as well as in those of Management, I usually base the whole semester of teaching on 4 – 6 comprehensive business cases. This time, during the winter semester 2018/2019, one of those cases was Tesla, and the main source material was Tesla’s Annual Report for 2017. The students who attended this precise exam were notified one week earlier that Tesla was the case to revise.
This said, let’s rock. Here comes the exam sheet:
Exam in Microeconomics February 1st, 2019
Below, you will find a table with selected financial data of Tesla Inc. Use that data, and your knowledge as regards the business model of this firm, to answer the two open questions below the table. Your answer to each of the questions will be graded on a scale from 0 to 3 points. No answer at all, or major mistakes, give you 0 points. Short descriptive answer, not supported logically with calculations, gives 1 point. Elaborate explanation, logically supported with calculations, gives 2 or 3 points, depending on the exhaustiveness of your answer. Points translate into your overall grade as follows: 6 points – 5,0 (very good); 5 points – 4,5 (+good); 4 points – 4,0 (good); 3 points – 3,5 (+pass); 2 points – 3,0 (pass); 0 ÷ 1 points – 2,0 (fail).
| Values in thousands of USD | |||
| Revenues | 2017 | 2016 | 2015 |
| Automotive sales | 8 534 752 | 5 589 007 | 3 431 587 |
| Automotive leasing | 1 106 548 | 761 759 | 309 386 |
| Energy generation and storage | 1 116 266 | 181 394 | 14 477 |
| Services and other | 1 001 185 | 467 972 | 290 575 |
| Total revenues | 11 758 751 | 7 000 132 | 4 046 025 |
| Cost of revenues | |||
| Automotive sales | 6 724 480 | 4 268 087 | 2 639 926 |
| Automotive leasing | 708 224 | 481 994 | 183 376 |
| Energy generation and storage | 874 538 | 178 332 | 12 287 |
| Services and other | 1 229 022 | 472 462 | 286 933 |
| Total cost of revenues | 9 536 264 | 5 400 875 | 3 122 522 |
| Overall total gross profit | 2 222 487 | 1 599 257 | 923 503 |
| Gross profit by segments | |||
| Automotive sales | 1 810 272 | 1 320 920 | 791 661 |
| Automotive leasing | 398 324 | 279 765 | 126 010 |
| Energy generation and storage | 241 728 | 3 062 | 2 190 |
| Services and other | (227 837) | (4 490) | 3 642 |
| Operating expenses | |||
| Research and development | 1 378 073 | 834 408 | 717 900 |
| Selling, general and administrative | 2 476 500 | 1 432 189 | 922 232 |
| Total operating expenses | 3 854 573 | 2 266 597 | 1 640 132 |
| Loss from operations | (1 632 086) | (667 340) | (716 629) |
Question 1 (open): Which operating segment of Tesla generates the greatest value added in absolute terms? Which segment has the greatest margin of value added? How does it change over time? Are differences across operating segments greater or smaller than changes over time in each operating segment separately? How can you possibly explain those phenomena? Suggestion: refer to the theory of Marshallian equilibrium vs the theory of monopoly.
Question 2 (open): Calculate the marginal cost of revenue from 2015 to 2017 (i.e. ∆ cost of revenue / ∆ revenue), for the whole business of Tesla, and for each operating segment separately. Use those calculations explicitly to provide a balanced judgment on the following claim: “The ‘Energy and storage’ operating segment at Tesla presents the greatest opportunities for future profit”.
Interpretation
Question 1 (open): Which operating segment of Tesla generates the greatest value added in absolute terms? Which segment has the greatest margin of value added? How does it change over time? Are differences across operating segments greater or smaller than changes over time in each operating segment separately? How can you possibly explain those phenomena? Suggestion: refer to the theory of Marshallian equilibrium vs the theory of monopoly.
The answer to that question starts with the correct understanding of categories in the source table. Value added can be approximated as gross profit. The latter is the difference between revenues and variable cost, thus between the selling price, and the price of key intermediate goods. This was one of the first theoretical explanations the students were supposed do start their answer with. As I keep repeating in my classes, good science starts with communicable, empirical observation, and thus you need to say specifically how the facts at hand correspond to the theoretical distinctions we hold.
As I could see from some of the exam papers that some of my students handed me back, this was the first checkpoint for the understanding of the business model of Tesla. The expression ‘operating segment’ refers to the following four categories from the initial table: automotive sales, automotive leasing, energy generation and storage, and services and other. To my sincere surprise, some of my students thought that component categories of operational costs, namely ‘Research and development’, and ‘Selling, general and administrative’ were those operational segments to study. If, in an exam paper, I saw someone calculating laboriously some kind of margin for those two, I had no other solution but marking the answer with a remark ‘Demonstrable lack of understanding regarding the business model of Tesla’, and that was one of those major mistakes, which disqualified the answer to Question 1, and gave 0 points.
In a next step, i.e. after matching the concept of value added with the category of gross profit, and explaining why they do so, students had to calculate the margin of value added. Of course, we are talking the margin of gross profit, or: ‘Gross Profit / Revenues’. Here below, I am presenting a table with the margin of gross profit at Tesla Inc.
| Margin of gross profit | 2017 | 2016 | 2015 |
| Overall | 18,9% | 22,8% | 22,8% |
| Automotive sales | 21,2% | 23,6% | 23,1% |
| Automotive leasing | 36,0% | 36,7% | 40,7% |
| Energy generation and storage | 21,7% | 1,7% | 15,1% |
| Services and other | -22,8% | -1,0% | 1,3% |
There was a little analytical challenge in the phrasing of the question. When I ask whether ‘differences across operating segments greater or smaller than changes over time in each operating segment separately‘, it is essentially a test for analytical flexibility. The best expected approach that a student could have developed was to use coefficients, like gross margin for automotive sales in 2017 divided by that in 2015, and, alternatively, divided by the gross margin on energy generation and storage etc. Thus, what I expected the most in this part of the answer, was demonstrable understanding that changes over time could be compared to cross-sectional differences with the use of a universal, analytical tool, namely that of proportions expressed as coefficients, like ‘A / B’.
As this particular angle of approach involved a lot of calculations (students could use calculators or smartphones in that exam), one was welcome to take some shortcuts based on empirical observation. Students could write, for example, that ‘The greatest gross profit in absolute terms is generated on automotive sales, thus is seems logical to compare the margin of value added in this segment with other segments…’. Something in those lines. This type of answer gave a clear indication of demonstrable understanding as regards the source data.
As for the theoretical interpretation of those numbers, I openly suggested my students to refer to the theory of Marshallian equilibrium vs the theory of monopoly. Here is how it goes. The margin of value added has two interpretations as regards the market structure. Value added can be what the supplier charges his customers, just because they are willing to accept it, and this is the monopolistic view. As the Austrian school of economics used to state, any market is a monopoly before being a competitive structure. It means that any relations a business can develop with its customers is, first of all, a one on one relation. In most businesses there is at least a small window of price, within which the supplier can charge their customers whatever he wants, and still stay in balance with demand. In clearly monopolistic markets that window can be quite wide.
On the other hand, value added is what the exogenous market equilibriums allow a firm to gain as a margin between the market of their final goods, and that of intermediate goods. This is value added understood as price constraint. Below, I present those two ideas graphically, and I expected my students to force their pens into drawing something similar.
Question 2 (open): Calculate the marginal cost of revenue from 2015 to 2017 (i.e. ∆ cost of revenue / ∆ revenue), for the whole business of Tesla, and for each operating segment separately. Use those calculations explicitly to provide a balanced judgment on the following claim: “The ‘Energy and storage’ operating segment at Tesla presents the greatest opportunities for future profit”.
As I reviewed those exam papers, I could see that the concept of marginal change is enormously hard to grasp. It is a pity, as: a) the whole teaching of calculus, at high school, is essentially about marginal change b) the concept of marginal change is one of the theoretical pillars of modern science in general, and it comes straight from grandpa Isaac Newton.
Anyway, what we need, in the first place, is the marginal cost of revenue, from 2015 to 2017, calculated as ‘∆ cost of revenue / ∆ revenue’. The ∆ is, in this case, the difference between values reported in 2017, and those from 2015. The marginal cost of revenue is simply the cost of having one more thousand of dollars in revenue. The corresponding values of marginal cost are given in the table below.
| Operating segment at Tesla Inc. | Marginal cost of revenue from 2015 through 2017 |
| Overall | 0,83 |
| Automotive sales | 0,80 |
| Automotive leasing | 0,66 |
| Energy generation and storage | 0,78 |
| Services and other | 1,33 |
Most of the students who took this exam, on the 1st of February, failed to address the claim phrased in the question, and it was mostly because they apparently did not understand what is the meaning of what they have calculated. Many had those numbers right, although some were overly zealous and calculated the marginal cost for two windows in time separately: 2015 – 2016, and then 2016 – 2017. I asked specifically to jump from 2015 straight into 2017. Still, the real struggle was the unit of measurement. I saw many papers, whose authors transformed those numbers – correctly calculated – into percentages. Now, look people. In the source table, you have data in thousands of dollars, right? A delta of $000 is given in $000, right? A coefficient made of two such deltas is still in $000. Those numbers mean that if you want to have one more thousand of them US dollars in revenues, at Tesla Inc., you need to spend $830 in cost of revenue, and correspondingly for particular operating segments.
Thus, when anyone wrote those marginal values as percentages, I was very sorry to give that answer a mention ‘Demonstrable lack of understanding regarding the concept of marginal cost’.
When considering the marginal cost of revenue as an estimation of future profits, the lower it is, the greater profit we can generate. With a given price, the lower the cost, the greater the profit margin. The operating segment labelled ‘Energy generation and storage’ doesn’t look bad at all, in that respect, certainly better than them ‘Services and other’, still it is the segment of ‘Automotive leasing’ that yields the lowest marginal cost of revenues. Thus, the claim “The ‘Energy and storage’ operating segment at Tesla presents the greatest opportunities for future profit” is false, as seen from this perspective.
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