### Windows 10 is still the mess that Windows 8 was

It doesn’t appear that Windows 10 cleaned up much from Windows 8.

After one day of using the former, it is easy to come to the conclusion that Windows 7 is still the last version that anyone should run on its merits. Nobody in their right mind appreciates the mess that is Windows 8/10. (This is not Microsoft specific either, as Yosemite is also the last version of macOS that seems worth one’s while. The mobile OS angle has addled the brains of program managers at these companies.)

More egregiously, Windows 10 (Home) is also crippleware. It has disabled a number of features out of the box. No Guest account. No Group Policy Editor*. And hilariously, in what must be an attempt to emulate macOS, it automatically restarts after a system update, but saves no program states, with obvious defective results.

* How do I know it’s crippleware? Because vestiges still remain. You can exhume Group Policy Editor from buried .mum files. While you’re at it turning Windows 10 back into some semblance of Windows 7, wouldn’t you like to also disable Cortana?

### usps insurance rates

What do USPS insurance rates tell us about its operations? Here is a 2007 document regarding insurance rates for domestic mail:

Prices for insurance coverage changed as follows:
Value up to $50 is$1.65.
$50.01 to$100 is $2.05.$100.01 to $200 is$2.45.
$200.01 to$300 is $4.60. The price per additional$100 of insurance, valued over $300 up to$5,000, is $4.60 plus$0.90 per each $100 or fraction thereof. Crudely taking the mid-point of each bracket up to$300, we get implied loss rates of 6.6%, 2.73%, 1.63%, 1.84%, respectively. The rate converges asymptotically to $0.90/$100, or 0.9% implied loss. The numbers have such a wide range that it’s worth taking a closer look.

### die throwing problem

Here’s a link to a subtle probability problem.

You throw a die until you get 6. What is the expected number of throws (including the throw giving 6) conditioned on the event that all throws gave even numbers?

The “obvious” answer is incorrect.

### Android Pay and mobile payment

I tried to use Android Pay twice today and despite both stores’ VeriFone terminals showing (and processing through the flow as if) they supported it, the success rate was only 50%. Android Pay is NFC-based. The time it succeeded, the phone immediately made contact. The time it failed, there was no semblance of any NFC connection. I know the phone’s NFC works in other contexts, so it is something in the technology (hardware, software) or workflow itself that makes it so unreliable. That is not even to mention the annoyance of Android Pay’s particularly patronizing attitude in requiring the phone to be unrooted and requiring a screenlock (even a perfectly insecure one) to be set. If any of those conditions fail for even five minutes, all the added cards are removed and have to be re-added (some banks require calling in for verification).

My point is nobody is going to use this idiotic piece of technology that makes things harder.

But mobile payment is not new. More than five years ago, a company called LevelUp started putting in QR-code based readers around town and having used it, it just works much better.

### Passing the Google “SafetyNet” test

If phone is rooted, follow the below steps:

1. Uninstall Xposed Framework
2. Uninstall Busybox
3. Fully unroot (not only uninstall)

Root is required to uninstall the first two.

### valuation of miles and points

As with any currency, the true value of various miles and points is determined by their trade value on a unified, liquid, and open market. Unfortunately such a market does not exist publicly — there is an underground secondary market with sometimes stale prices, minimum trade requirements, and counterparty risks, but generally speaking there is no notion of transparent prices. So you often see “Mileage Blogger” sites like this bandying about valuations pulled out of thin air. There should be a much more principled way to determine valuation that helps to make transaction decisions easier.

### Built-in audio variations

In light of Apple’s removal of the 3.5mm jack (for which there is an excellent analysis), I must say that there is something to be said for the inconsistency of analog audio output from built-in audio devices in laptops. Apparently there is quite a bit of variation that I hadn’t realized.

I ran this test using two sets of fairly wideband headphones and got results that were consistent across headphones but different between an HP laptop and a MacBook. The headphones were rated, respectively: (1) 15 – 20,000 Hz, 47 Ω input impedance; and (2) 15 – 24,000 Hz, 35 Ω input impedance. On the HP laptop with “IDT High Definition Audio” (92HD93 chip), I could hear a range from 30 Hz to 18 kHz. On the MacBook Pro with mid-2014 hardware, I could hear a range from 20 Hz to 16 kHz. I was quite surprised at the magnitude of this difference. A headphone amplifier (e.g. one built into the headphones) driven by digital input would eliminate this difference.

### optimizing insurance ordering

Sometimes the order in which procedures are performed has an effect on the payout from insurance. This is the case when there is both a deductible and a coinsurance.

Suppose the deductible is $$d$$, and the price and coinsurance of the $$i$$-th procedure performed are $$p_i$$ and $$c_i$$ respectively, then the total out-of-pocket cost is:

$$d + (p_1 – d) c_1 + p_2 c_2 + \cdots = (1-c_1) d + \sum_i p_i c_i$$

The second term is fixed cost; it’s the coinsurance on the first procedure that matters. This shows that to minimize out-of-pocket cost, one should, somewhat surprisingly, get the procedure with the highest coinsurance first. Essentially, every dollar of the deductible paid is subsidizing what the insurance company might have paid, but for a procedure with very high coinsurance, the subsidy is not very much to begin with.

### The non-existence of Android backup and restore

People change phones. They want their programs and data to show up on their new phones. Apple has solved this problem. Somehow, Google has not. As explained here, settings can be synced through Google’s sync API. It is however useless except for Google’s own apps and whoever uses their API (maybe nobody).

But as far as full-system backup and restore options go, you either have to root your system and use Nandroid or Titanium to backup to the phone storage itself, or you have to rely on adb backup. adb is Android Device Bridge, something that is accessed through the Developer Mode on Android. It feels like Google has given up on this feature midway through and just left it flopping around, because it simply does not work. Although I haven’t had trouble getting backup to work (‘adb backup -apk -shared -all -f [file]‘), I could not get restore (‘adb restore [file]‘) to work automatically because of this bug (which incidentally is also obsoleted).