From the Stanford Encyclopedia of Philosophy:
We must often make decisions under conditions of uncertainty. Pursuing a degree in biology may lead to lucrative employment, or to unemployment and crushing debt. A doctor’s appointment may result in the early detection and treatment of a disease, or it may be a waste of money. Expected utility theory is an account of how to choose rationally when you are not sure which outcome will result from your acts. Its basic slogan is: choose the act with the highest expected utility.
Expected value is basically the same thing except we're talking about value more generally rather than utility, which is a specific way of measuring value.
Basically, it's a weighted average where we look at what the possible outcomes are, how much we value each outcome, and what the probability of each outcome occuring is. Measuring things in dollars is useful because we have an intuitive sense of how valuable a given number of dollars are.
Why make decisions according to expected utility? Here's the Stanford Encyclopedia of Philosophy again:
Expected utility theory, which holds that a decision-maker ought to maximize expected utility, is the prevailing theory of instrumental rationality.
I have two thoughts on this objection.
One is that this app might not be for you. If so, that is ok. But I believe that there are people out there who would find it useful. And related to the idea of 1,000 True Fans, the app could still be worthwhile even if the target audience is small.
My second thought is that the analytical approach might be like green eggs and ham. Try it, you'll like it!
And recognize that the point of such exercises isn't to put blind faith in the resulting numbers. It's to help build your intuition. I like the way it's explained in Harry Potter and the Methods of Rationality:
Harry was wondering if he could even get a Bayesian calculation out of this. Of course, the point of a subjective Bayesian calculation wasn’t that, after you made up a bunch of numbers, multiplying them out would give you an exactly right answer. The real point was that the process of making up numbers would force you to tally all the relevant facts and weigh all the relative probabilities.
Y'know, I'm not quite sure. My main motivation might be just that I think this should exist. And along those lines, I guess I'm inspired by Paul Graham's heuristic to "live in the future, then build what's missing".
But I also have some more concrete thoughts. Ultimately I'd love to convince more people to bike. Once in front of people, I'm hoping that this app can do that. And as for how to get it in front of people, I dunno. Probably some combination of word of mouth and promotion by bike advocates. I also kinda want to set up a table at the farmer's market and promote it there.
Ultimately I'm open to different directions things could go.
I do have an agenda. I think the world would be a much better place if lots of people switched from driving to biking, and I hope this app convinces more people to do so.
I take a lot of pride in being open-minded and intellectually honest, but I'm also not perfect. Despite my efforts, I expect that my biases have crept in to a small degree. Possibly a medium degree.
But you probably shouldn't even trust me there. The fact that I am pretty intellectually honest is information that is private to me. From your perspective, a stranger is putting forth the claim that they are intellectually honest, and that probably shouldn't sway you too much.
I'd like to say that you don't have to trust me, that you just have to trust the numbers, but that probably isn't true. You can lie with statistics, and more generally, you can lie with numbers.
But despite all of these blemishes, I still think this app offers a fair amount of value. Other tools and sources of information have all the same problems. In fact, I think this app probably compares pretty favorably to other stuff. And there's only so far "lying with numbers" can go in this context.
The slider represents a range of possible values that I think are plausible. It doesn't prevent you from typing in a value outside of that range.
The default value isn't necessarily going to be in the middle of that range. Often times it isn't. Often times I think values can vary by orders of magnitude. Maybe in the future I'll build a logarithmic slider.
Sorry about that. I tried to do a solid job here but ultimately this is a side project that is still a work in progress, and I'm not an expert. Please shoot me an email if you have any suggestions.
When you see something like "↘︎ $15" it means the current value is $15 lower than the baseline value. You can update the baseline values of all inputs by clicking the "Set as baseline" button at the bottom of the page.
Here are some initial ideas I have:
I don't want to get too attached to any of these ideas though. I want to get "pulled" into things by users as opposed to "pushing" things onto users.
You can still use the app, you'll just probably end up entering differnet values for the parameters than you would if you were riding a regular bike.
Relative to regular bikes, e-bikes are more expensive, get you to your destinations faster, don't give you as much exercise, arguably are safer, and often are more fun!
Already owning a bike or a car will mean that the cost per month will be lower, but not zero. There are still costs like maintenance, gas, insurance, parking, depreciation, taxes and fees. Right now the app doesn't do much to help you figure this all out but hopefully in the future it will.
Or, depending on how you're approaching the analysis, you also might want to take that upfront cost that you already paid and spread it out over the lifespan of the bike or car. Like if you bought a $1,000 bike that you expect to last 10 years, you might want to add $100 per year to the cost of biking.
Right now the app the app compares the expected value of 100% driving to 100% biking. In reality most people won't fall exclusively into either of those buckets. However, accounting for mixed modes of transport adds a fair amount of complexity and right now I want to keep things simple.
In the future I might give mixed modes a stab. For now, hopefully the single-mode analysis can help you get a ballpark idea of what the results of a mixed-mode analysis might look like. For example, if the single-mode analysis says that biking is +$750/month, if you have good bus service available, a mix of biking and taking the bus might be +$900/month instead of +$750/month.
Eh, not really. You could try to mess around with the inputs to come up with a per-trip analysis, but I think that'd be fighting the tide too much. Maybe in the future I'll add functionality to help with per-trip analyses.