If conception is totally random, sure. But it could be a lot lower than that if you were making that your goal. Suppose that a couple tried their best to get pregnant every January 1. Assuming they succeeeded, you’re looking at a September birth with a range maybe a couple weeks?
So you have your first child. on Sept. 15. Then to have two more on that date it is:
[P(ovulating on Jan 1) x P(hit exact Sept. Date)]^2
I’m suggesting that the value on the right is 1/14, so it is
1/196 x P(ovulating)^2
Not a uniform distribution on the delivery date. Even ignoring that if it’s close in either direction mom has some say in when to ask for a c-section, the probability of delivering on the due date still won’t be uniformly distributed.
According to this article, September dates are the most common (those cosy December get-togethers) -
The most common birthday is Sept. 9. In second and third place are Sept. 19 and 12.
Also, as mentioned elsewhere, C-sections can be somewhat planned -
According to a working paper from the National Bureau of Economic Research, there are 18% less births on the day of and just after a holiday. Around half of the decline is due to fewer cesarean sections scheduled on holidays, in part because of low hospital staffing numbers on the holiday and cultural attitudes — parents’ desires to separate fixed holidays and birthdays.
I’ve also heard of avoiding it happening being the goal - an overdue pregnancy being induced the day before a siblings birthday so that they didn’t coincide.
Is this to what the article is referring?
Because, I’m gonna guess that was not random, so the “odds” do not apply. That is a cray-cray wanting attention.
I’m surprised December 31 is so far down the list. I thought people induced on the 31st for the tax deduction.
One place I worked would list everyone’s birthday and there were a TON on 12/31. A typical December day had maybe 2 or 3 birthdays and then 12/31 was in double digits.
More change of assumption rather than innumeracy, but certainly unusual.
I reset the trip odometer on my car when I fill up the gas tank.
Today, before starting a long trip, odometer was at 215, and car was telling me (automatic readout) I had enough gas left to go 150 miles. Certainly, most of the 215 had been on drives of less than 20 miles from home (mainly suburban driving, included some stretches of about 10 miles of interstate).
When odometer reached 260 (after 45 miles), I had enough gas left to go 150 miles. When it reached 265, I had enough left for 160 miles. After than, reasonably close to expected (odometer ending between 290 and 300, with enough gas for 130.)
I think it is more of a question of how the “range left” calculation works. Sure, it looks all authoritative, but without knowing exactly how it works, I’m skeptical.
That makes me a Luddite in the most strict definition, I suppose, but Luddite I will be if I do not have some explanation that I can understand.
And I know that people here have an idea of how it works, reverse-engineering the way based on empirical evidence, and they’re ok with an estimate.
Once, I filled my wife’s the tank with a few gallons (Note: my old-ass car has no such reading) when it was near-empty. The computer was not capable of adding 100 miles or so to the range left based on there being more gas in the car. So, the range stayed where it was, basing the calculation on what it already calculated when the tank was full.
I took my gf to Hobby Lobby when we were in the US of A a couple of weeks back. She bought $39.30 of stuff and gave the high school aged cashier $40.30. He said he couldn’t do the math and gave back her original 30 cents plus another 70 cents in change.
I don’t know. The car is a 2012 Subaru Outback, if anyone wants to try to Google their logic. In fact, most of the first 15 miles was on a fairly crowded interstate, averaging maybe 40 mph (never reaching 60). After that, most was interstate or similar, driving pretty consistent 65ish.
I’d wager that part of the computation isn’t based on the car “knowing” how much gas is actually in the tank. Rather, there’s a “trigger” to indicate that the tank is full and when the tank is “low”–which the computer knows the capacity of the tank at these two trigger points.
And the algorithm is based on aspects that the computer is set up to monitor: fuel consumption and distance driven. Setting things up to monitor actual fuel level in the tank might be a cost the manufacturer is willing to cut.
I drive a 2014 Subaru Forester. Based on my own casual observation of the estimated fuel ranges, I think the algorithm behind the display is:
[Amount of fuel detected in tank] / MIN([Fuel economy over past n kilometers], x)
I haven’t cared enough to work out n and x.
I formed that hypothesis just by casually watching the behavior of the estimated range after filling up my tank. When I fill up after having taken a summer road trip with more efficient driving and higher-energy fuel, the estimated range will be rather large. When I fill up after having puttered around town in the winter, where traffic, traffic lights, terrain, and fuel blend all degrade mileage, the estimated range will be rather low.
I think there’s a ceiling on the fuel economy assumed, because on long trips, I consistently beat the estimated range. I wouldn’t be surprised if there’s also a floor…but that’s not something I’ve tried to test or had reason to experience.
If I start with a full tank of gas there have been times I’ve made the drive to the next city over, roughly 100 miles, with the same “miles to empty” as when I left. It’s like Scotty beamed me there.
The low warning light comes on roughly when the calculation shows 60 miles left. I know I have sometimes let it get down to 10 before refilling. Sounds like I was lucky.
Manual also seems to say I can see my average MPG since last reset of the trip odometer (separately for A and B trip odometers, though I never worry about the difference between A and B.) It doesn’t tell me which of those the estimated driving distance is based on. It says I can also see my current MPG. (only one of the three at a time, can toggle which). I’ve never noticed that display, which is not part of the main dashboard display. The toggle has 4 settings, also including “blank”, which is likely the reason I’ve never noticed it.
It also has an ECO-gauge, which tells me (on a very nearly useless uncalibrated scale) the difference between average rate of fuel consumption since the trip odometer was last reset (not sure whether than means A or B or whichever was most recent) and the current rate of fuel consumption. A stupid gauge I always ignore.
