Category: statistics
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Excel trick: Search for multiple keywords from a list
Recently I was given a large spreadsheet with people’s expertise written in long phrases, and I had to identify those people who have AI-related expertise. The issue here is that people can enter a variety of phrases such as “machine learning”, or “large language model”. How do I quickly identify those people? Fortunately we can…
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EV has come a long way but US is falling behind
I came across the data of EV stock at the country level from the IEA website. While it is informative, it does not have any map visualization, which is quite easy to do with Excel. So I just did that. The above is the one on EV stock in percentages by country as of 2022.…
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EV Charging Networks: The Top 8
In the EV book that I co-wrote and co-edited (with Peter Fox-Penner and David Jermain) in 2019, we documented the status of EV charging infrastructure in cities around the world such as Los Angeles, Oslo, and Beijing. Since then, EV adoption has continued to grow by leaps and bounds. In this post, I intend to…
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How much do you pay charging an EV on a monthly basis?
I always knew it is a bit cheaper to drive an EV as opposed to a gasoline car (not the owning part, which deserve a separate calculation, but just the day-to-day cost of using it) in New England where I live, but I never bothered to quantify that saving. That is, until today. As you…
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Why Supply Chain Delays are Multi-faceted: A Mathematical Explanations (Without the Heavy Math)
Paul Krugman recently penned an excellent article explaining why we see the supply chain snarls in New York Times. It mentioned a number of factors: The US consumers are buying a lot more stuff than before, as a partial substitutions to experiences because of the COVID; The processing capacities at docks and hubs have not…
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Understanding CO2 Emissions for different freight transport modes (renewable as well as non-renewable)
One of the most important questions to ask in transitioning to renewable modes of transport is simply: How much less CO2 are we going to emit by switching to renewables? The other important question is: How much does it cost? I have been researching on that question quite a bit. And I found quite a…
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Tesla Lease Mileage Limit and the Central Limit Theorem
I am onto my second Tesla car leases now, so I think I can define another form of range anxiety with my leased cars: Driving over the lease limit. It was actually quite interesting. When I was leasing my first Tesla, I did a rough calculation of my daily driving, and figured that 10,000 miles…
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SHOULD I BUY OR LEASE A TESLA? PART 4: It all comes down to your apetities towards risk
Having used multiple spreadsheets to illustrate the dollars and cents around the leasing vs buying option, let me conclude. It depends on how you view uncertainty. As I said earlier, one big advantage of leasing is its clarity and certainty. You know how much you are going to pay, and that is how much it…
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SHOULD I BUY OR LEASE A TESLA? PART 3: It is not black-and-white (because we do not know the future)
In my last post, I showed that the total cost of buying a Tesla with a loan (or cash) is easy to figure out. However the final value is critically dependent upon one thing: the depreciation of the car when the owner sells it. Unfortunately that quantity is uncertain, because it has not happened yet…
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SHOULD I BUY OR LEASE A TESLA? PART 2: Total loan cost (when you are sure about the depreciation)
In a previous post, I calculated the total cost of leasing a Tesla, using my own experience as an example. Before we move on to the buying option, let me mention one important feature of leasing: It has more certainty in terms of total cost. You know what you pay, and you do not worry…
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Should I Buy or Lease a Tesla? Part 1: Leasing Cost
Recently I read quite a bit of discussion on “Should I buy or lease a Tesla?”. I do not want to weigh in on which side I take, as I know it is not just about numbers. People value things differently. So here I would just focus on the monetary cost side. When it comes…
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How to draw ranking data properly
A slight problem with drawing data on ranking is how we normally think about ranking. We normally associate “#1” as the best, and “#10” as worse compared to “#1”. But Excel chart typically shows a bigger number in a higher vertical position, and a smaller number in a lower position, as is shown in the…
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Simulation: Is demand equal to sales? (Part II, and why is there a Loch Ness Monster?)
In an earlier post, we discussed the difference between demand and sales using a simulation exercise. Now the question is: How can we visualize the difference? To start off, we all know the shape of the normal curve (in the example we discussed the mean is 600, and its standard deviation is 100): However, if…
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Simulation: Is demand equal to sales? (Part I)
Consider the following problem: Suppose at a retail store the annual demand for a toy is a random variable with a normal distribution of N(600, 100), i.e., with mean of 600 and standard deviation of 100. Simulate the distribution of sales if 700 units of such a toy is ordered. What is the expected sales?…
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Simulation: It all starts with a coin toss
There are many sophisticated tools dedicated to Monte Carlo simulation, but Excel is powerful enough to handle a variety of simulation needs. Here are the basic steps of simulation in Excel. First the users build a decision model in a spreadsheet and specify what are the sources of uncertainty. Excel can then generate random numbers…
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Last-mile Transport is the Key Driver in Supply Chain Carbon Footprint
Does online shopping have a larger or smaller carbon footprint? Well, it depends. But depends on what? In a most recently-published study by Shahmohammadi et al (2020) published in Environmental Science & Technology, the authors highlight that the last-mile transport is one of the most important drivers of carbon emissions, among other things. What I…
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Carbon Foot printing: Devil is in its details…
I have been reading up on the carbon foot printing work lately. A lot of interesting findings. Overall, my impression is that the modern e-commerce is not significantly improving our carbon footprint. And with customers’ adaptive behavior (e.g., ordering more, not giving up store trips), it is likely that we can end up with a…
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Zero-Carbon Economy: A Grand -and Necessary – Vision
I just watched a video produced by Cambridge University called “The Climate Crisis: Towards Zero Carbon”: Well done, Cambridge! The video first shows that data on historical CO2 levels and temperature makes it irrefutable that the current climate crisis is created by us humans. The video then highlights a few important areas for decarbonization: Energy…
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ICCT’s Report on the Lifecycle Comparisons of GHG Emissions of Gas Cars vs. EV is Filling a Void
Today The International Council on Clean Transportation release a report called “A global comparison of the life-cycle greenhouse gas emissions of combustion engine and electric passenger cars“, which I find a satisfying read. Its key findings can be highlighted in the following graph: The graph is quite dense, so let me point out a few…
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Modeling Driving Distances (3)
Since my last post on using NTHS dataset to fit people’s driving distances, I have made some further modifications: (1) There are some very large TRPMILE data values, in the order of 1000 miles. While there are most likely valid data – After all, people do travel that far – I realize that this is…