swapped.cc/blog

A blog by Alex Pankratov

[swapped]

No Emails on Saturdays

The last time I sent out an update for one my projects, I did it a bit differently. Instead of mailing all 2000 subscribers on the mailing list at once, I sent the newsletter in 5 batches, one batch a day, from Saturday to Wednesday.

This was three weeks ago and today I got around to looking at the stats.

The opening rate

Long story short -

Saturday - 27.7% (lowest) Sunday - 40.3% Monday - 39.1% Tuesday - 46.3% (highest) Wednesday - 44.3%

With the overall opening rate being 39.4%.

So it’s painfully obvious that people don’t like receiving newsletters on Saturdays, and that they probably have better things to do on Mondays too.

The engagement rate

To understand this metric, take at the actual newsletter.

It announced the completion of the website redesign and then asked if the redesign was good or not. So the engagement simply tracks how many people bothered to cast a vote -

Saturday - 25 Sunday - 47 Monday - 35 Tuesday - 35 Wednesday - 39

With these numbers in mind, the corrected take away is this -

Not on Saturdays. Not on Sundays or Mondays, but if pressed, pick Sundays.

Whether Tuesday or Wednesday is optimal is an open question. If I haven't had a brain spasm and picked 7 days instead of 5, we might've had an answer. But my guess would be that with an exception of Monday (and possibly Friday) all mid-week days perform about the same.

For those arguing that the data sample is too small - yes, it is, but it doesn't preclude making general observations and validating them against, you know, common sense.

In any case, raw data is below. Take a look if interested.

Fine print

Each batch worked out to be about 400 emails and they were grouped by (Subscriber-ID mod 5), where ID is a basic incrementing integer. So for all intents and pseudo-scientific purposes all batches had roughly the same mix of early/late subscribers.

The newsletter was sent out at (North American) night, so the emails were in the inboxes, when the majority of subscribers checked their mail in the morning.

Comments

https://news.ycombinator.com/item?id=5236970

Raw data

emails visits votes Sat 401 111 25 Sun 389 157 47 Mon 379 148 35 Tue 378 175 35 Wed 400 177 37

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Novel optimization technique

Consider a snippet of code that goes through a list of items to find one that matches a condition. For example, searches for a [heap](http://en.wikipedia.org/wiki/Memory_management#Details) bucket suitable for allocating a memory block of a certain size: bucket_t * b; size_t i, n; ... for (i=0, n=heap->bucket_count, b=heap->buckets; i < n; i++, b++) { if (b->size_min <= size && size <= b->size_max) break; } Now, check this out. Adding a line of code that is completely pointless - ... { if (b->size_min <= size && size <= b->size_max) { b = heap->buckets + i; // b is already exactly that ! break; } } speeds things up by 5% ! --- The code uses [__restrict](http://msdn.microsoft.com/en-us/library/5ft82fed(v=vs.80).aspx) qualifier for the pointers and it is compiled with all reasonable speed optimizations enabled. And yet, adding a bit of useless code somehow lets the optimizer do a better job. Go figure. Courtesy of Microsoft Visual C compiler, vintage of 2010.

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Extended default arguments / C++

It'd be nice if C++ would allow overriding selected default arguments and preserving the rest. Specifically, given a declaration like this - void foo(int a = 0, const char * b = NULL, T * c = NULL); the following is supported - foo(100); foo(100, "bar"); but the following is not, though it's a natural extension of the same idea - foo(, "baz"); foo(678, , &x); In fact, it'd be very nice if C would support this as well.

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Retina support, Windows-style

Every bit of graphics that goes into a modern Windows app must be done in at least three different sizes - one for each common screen DPI level.  DPI stands for dots-per-inch and it’s a metric of a pixel density, in our case - on the screen. The smaller the screen, the more pixels are packed into a square inch if the resolution remains the same. The difference in DPI between a large LCD panel and a 12” notebook screen can easily be a factor of two or more. This means that if a program renders 9px text on both screens, on one it will appear twice as small as on the other one, and might command a need for a magnifying glass. Naturally, it’s a good idea to make the OS aware of the actual DPI of the monitor in use. If it’s too high, the OS can do few things to make things visible with a naked eye again. Like increase size of the default system font and make windows and controls generally larger. This can be done automatically by looking at the monitor .inf files or by letting the user [configure the DPI manually](http://www.techrepublic.com/blog/window-on-windows/get-a-better-view-in-windows-7-by-adjusting-dpi-scaling/5404). — XP defaults to 96 DPI and with some difficulty it can be changed to 120 DPI. Vista and newer versions are better. They come with four predefined levels - 96, 120, 144 and 192 - and they also support custom settings. This brings us back to needing multiple versions of every graphic in the app. — Vista is the first Windows version to routinely use monitor-specific DPI values out of the box. As such 96 is no longer a dominant DPI level and the apps are now expected to take the DPI into an account when rendering their content. The higher the DPI, the larger the graphics and the fonts the app should use. Hence the need for 3+ differently sized copies of the same pixel art. The penalty for not doing this is an automatic stretching of the app window that inevitably leads to a blurry appearance and a host of [other lovely issues](http://msdn.microsoft.com/en-us/library/windows/desktop/dd464660%28v=vs.85%29.aspx#common_high_dpi_issues). In other words - not complying with the OS expectations is not really an option. For more info check [here](http://msdn.microsoft.com/en-us/library/windows/desktop/dd464660%28v=vs.85%29.aspx) and [here](http://www.rw-designer.com/DPI-aware).

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How to Stop Forum Spam

Say you make and ship a software product. Chances are that you also maintain a public forum in the support section of the website. It is also highly likely that you have a problem with spam. Any public forum with open positing policy quickly deterriorates into a dump. A conventional way to deal with this is to require creating an account, solving a captcha and then validating the email address. This is not good, this is a hassle. Consider someone who just downloaded the product, tried it and on the spur of the moment decided to tell you all that there's to tell about it. That's an impulsive feedback - very precious, very useful. The last thing you want is to drag this person through the hurdles of registration. Alternatively, you can let anyone post, but hold initial posts in the moderation queue. This is not good either, because it's a hassle too, but this time it's yours. But there is a better way. --- You can tell a human from a spam bot by the way they move through the site. Humans typically come through a referrer, they look around, they scroll pages, they download the program and only then come to the forums _to post_. On the other hand, bots are simplistic - they come, they post, they leave. Ain't this difference plenty enough to guess a human? I think it is. So, instead of disallowing anonymous posting and requiring captchas, drop a cookie and look back at visitors' history on the site. If it checks out, let them post, no strings attached. If it doesn't, well... there's that chance to annoy them with captcha. --- Discussion on HN - http://news.ycombinator.com/item?id=4809007

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Relative relative symlinks

If you have been around computers long enough, you probably know what a [symlink](http://en.wikipedia.org/wiki/Symbolic_link) is. It is also likely that you've created at least one relative symlink that was pointing up the tree and then back down to a sibling directory: foo.txt -> ../../bar/foo.txt But here's something that you probably don't know, and it's as confusing as it is useful. ---- Consider the following directory layout: entry/ foo/ linked-1 -> ../../linked-1 linked-1/ bar/ linked-2 -> ../../linked-2 linked-2/ document.txt Let's `cd` into `entry` and follow first symlink: alex@box:~$ cd entry/foo/linked-1 alex@box:~/entry/foo/linked-1$ ls -l drwxr-xr-x 2 alex alex 4096 Nov 7 12:25 bar Works as expected. Let's `cd` into `bar`: alex@mx:~/entry/foo/linked-1$ cd bar alex@mx:~/entry/foo/linked-1/bar$ ls -l lrwxrwxrwx 1 alex alex 14 Nov 7 12:25 linked-2 -> ../../linked-2 **Now, observe closely**. `linked-2` points to a non-existent `~/entry/foo/linked-2`, so the following shouldn't work: alex@mx:~/entry/foo/linked-1/bar$ cd linked-2 ... But it does: ... alex@mx:~/entry/foo/linked-1/bar/linked-2$ ls -l -rw-r--r-- 1 alex alex 0 Nov 7 12:35 document.txt Ha! Didn't see that coming, did you? Neither did I :) ---- Symlinks are resolved in a context of their _native_ directory, even if that directory happens to be presently traversed under a different name (and therefore with a different absolute path).

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Re-subscribe

One of my projects got upgraded to a fancy HTML newsletter and it looked like a good opportunity to do something interesting with an obligatory Unsubscribe link.

Conventionally, the link leads to another page that acknowledges the unwelcome news, confirms the unsubscription and pleads to undo the mistake - we are sorry to see you go, yadda yadda.

I thought I'd try and keep things simple and streamlined at the same time. Like so:

Things to note:

All relevant information and all interaction is restricted to a small area of the same page, not 600px worth of text on another page... that also happens to be styled differently.

The Yes/No step is a conservative safeguard that catches those clicking on Unsubscribe accidentally or out of curiosity.

Technically speaking, such people can always re-subscribe, but in reality there will be some who won't. Every subscriber is valuable, so it's better be conservative and prevent rather than proactive and undo.

Re-subscribing is a one-click operation.

Showing a Re-subscribe link seems like an obvious idea in retrospect, but it took me a while to converge to it.

When a page realizes that a visitor is a past subscriber, it shows Re-subscribe link instead of a more general Subscribe option. This facilitates bringing past subscribers back on the list.

Live demo (scroll to the bottom)

My minimalist interface collection

† Obviously enough, this is for web versions of the newsletters, and not for those sent out by email. Latter are barely stylable, leave alone being scriptable (link).

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Pre-launch promotion in numbers, part 2

Here's a paid tweet that went out on Friday morning.

Here's the summary of how it worked:

12,000 followers

12 clicks

1 new subscriber (to the mailing list)

The tweet cost $100 and it was purchased through BuySellAds. Needless to say, it wasn't worth the money.

It's also worth noting that BuySellAds claims that there were 10x more clicks than what my server-side analytics recorded:

Even assuming that they do not exclude bots (which they should) and that some visitors might've had their Referrers blanked, it's still quite a discrepancy.

See also Pre-launch promotion in numbers, part 1.

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Google Bot now crawls arbitrary Javascript sites

Just spotted something while looking through Apache logs:

66.249.67.106 ... "GET /ajax/xr/ready?x=clcgvsgizgxhfzvf HTTP/1.1" ...

This is an ajax request issued from document.ready() callback of one website's pages. This means that the bot now executes the Javascript on the pages it crawls. The IP of 66.249.67.106 is crawl-66-249-67-106.googlebot.com and the A record is a match, so this is in fact a Google Bot.

Moreover, few lines below there is this:

66.249.67.106 ... "GET /content/halloc/index.html?&x=clcgvsgizgxhfzvf ...

This is an URL that is fetched via Ajax by a Javascript function in response to the menu item click. Also, note the x argument - it is dynamically added and only by that specific function. This means that the bot now emulates a user clicking around the site and then seeing which actionable items lead to which additional pages.

This is pretty incredible in and of itself.

It also means that Google Bot has smarten up to a point where it can crawl an arbitrary Ajax'ified website and not "some dynamic comments" as before.

Good stuff, never liked that escaped_fragment contraption anyway :)

[swapped]

#! tweets

Here's a functional reduction of the pinned tweets idea from yesterday.

Instead of relying on Twitter to support pinning, it is perfectly possible to do it entirely on a client side. I hereby present you... a drum roll...

THE #! TAG

I propose to adopt a convention whereby adding #! tag to a tweet marks it as important. Then when a twitter client on the followers' side is readying such tweet for showing in the UI, it will replace original timestamp with current date and time and this will automatically place the tweet at the top of one's feed.

To curtail the abuse, the twitter client should also allow disabling this behavior either globally or on per-user basis.

Obviously, a bit of coordinated effort from major twitter client developers is needed, but given the positive effect of this change on the overall Twitter experience, I don't think it's that much to ask :)

So, TweetDeck, HootSuite, EchoFon, TapBots, Twitterrific, what do you say?

† If you are having a WTF moment, have a look at the Pinned tweets post.

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Pinned tweets

If you use Twitter, you've seen [promoted posts](https://business.twitter.com/advertise/promoted-tweets/). They are essentially a form of random spamming on Twitter's part, routinely irrelevant and hardly ever interesting - nothing more than an annoyance.  On the other hand, there are some tweets that I actually *want to see*. For example, there are news and updates posted to company's accounts. These are infrequent, released unpredictably and they are exactly the reason why I am following these accounts in the first place. But they get lost in the noise. What Twitter needs is an ability to **promote tweets to the followers**. ---- The idea is to reserve the top part of my tweet stream for tweets that are promoted, or *pinned*, by their posters. This way if I go on a vacation and a vendor ships an update, I will still see the news when I get back:  Once a pinned tweet is shown to me, it starts dropping down in my timeline as usual. Think of it as a delayed, on-demand tweet delivery. It also makes sense to allow posters to _un-pin_ their tweets to allow delivering short-lived, expiring news such as this:  And that's it - an intuitive and useful extension to the Twitter mechanics. --- Also consider this: * Pinning essentially lets posters mess with their followers' streams, which is something that requires a great degree of restraint and diligence. As such it has a property of *self-correcting the abuse*. You start pinning too many tweets - you will see me promptly unfollow you. * Secondly, pinning is a form of relevant advertising that is actually useful. I am an ardent AdBlock user of several years, and this is the first time I am actually *asking* for ads. Take a second, let this sink in :) Lastly, this should be very easy to monetize _and_ on an absolutely massive scale. There's not a single person who wouldn't want or need to pin a tweet now and then, especially if it's an affordable thing to do. --- † Yes, there are [Twitter lists](http://support.twitter.com/articles/76460-how-to-use-twitter-lists), and, No, they are just not convenient enough. ‡ A discussion thread - http://news.ycombinator.com/item?id=3971933 --- **Update** The "#! tweets" is the Version 2 of the same idea. [Have a look](http://tmblr.co/ZAzGvxLUmMHy).

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An internal analytics dashboard for [Notwerk](http://notwerk.com)

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Pre-launch promotion in numbers, part 1

**Notwerk** site has been up for several days and I thought I'd share some numbers. First of all, the site is a [single teaser page](http://notwerk.com), it is meant to introduce the product and to try and get those interested to subscribe to updates and to help spread the word. During the first week we went through a list of simpler options that were either free or relatively inexpensive including BetaList, Reddit, StumbleUpon, Twitter, Dribbble and Forrst. There's plenty of metrics that can be used to measure the traction, but at the end of the day, the only metric that really matters at this stage is how many people joined the mailing list. And so here it is:  The net result - 235 subscriptions, 208 - confirmed (by clicking on a link in email). The breakdown in the lower part shows which domains drove the subscription activity and there are few take-aways: * [BetaList](http://betali.st) is not just a great source of sustained subscription flow, but it also has the highest confirmation rate, which is obviously important. It also spawns a mini-storm of retweets, which is always nice to have. Kudos to [Marc](https://twitter.com/marckohlbrugge) for the site. * Reddit is a reasonable source of traffic. I ran a [promoted post](http://www.reddit.com/comments/t0sxj/announcing_notwerk_a_massively_distributed/) in /r/networking and /r/sysadmin for 3 days, costing $250 and yielding 1% click-thru rate and 44 confirmed subscribers, i.e. about $5 each. I also suspect that making a regular post could've worked as well if not better. * StumbleUpon is an utter waste of time and money. From 300 visitors they sent (presumably from an IT audience) only 10 did *not* leave within 2 seconds, and none subscribed or tweeted. Subscriptions from ycombinator.com are an accidental scatter from somebody submitting a link to the Notwerk's [/no-script](http://notwerk.com/no-script) page. Next week we'll be moving to heavier and costlier promo methods and I'll try and post the findings. [Follow](http://twitter.com/apankrat) if interested. [Alex](http://swapped.cc/about)

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Test of [Paper](http://www.fiftythree.com/paper/via/tumblr)

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Fast-track patents

The following is based on my exchange with the US patent attorney in late 2011. If you have an US patent application pending a review, I would strongly advise to read on.

tl;dr

The USPTO has a new prioritized patent application review process that is about twice as fast as the conventional one. Any pending US patent application is currently at risk of a competing application getting granted if latter is fast-tracked even if it was filed on a later date.

The way to protect against that appears to be to request the USPTO to publish your application now instead of waiting until it is reviewed and the patent is granted.

Priority examination

I filed a patent application not long ago. A couple of weeks ago I received an email from the patent attorney:

Not sure if this would be of interest to you, but wanted to bring to your attention that as part of the newly enacted America Invents Act, a prioritized examination process (called "Track I") is available for US Patent Applications.

Under the prioritized examination process, the USPTO's goal is to bring the examination process to closure (e.g., final rejection or allowance) within one year. This is twice as fast compared to the regular processing times, which are about 25 months as of November 2011.

So what are the conditions?

To participate in the program, we would need to file a continuation patent application from your currently pending application and concurrently submit a request for prioritized examination along with the patent application filing fees (approx. $500) and a prioritized examination fee of $2,400.*"

Additionally - and that's where things are starting to get funny - one can request upto 20 claims to be examined at a priority. If the application contains more claims than that, it would effectively be split in two and each part be examined separately, at different times.

The problem

Having mulled over parting with $2900, I decided to double-check something first -

Say someone files an application (A), then someone else files a copy of A and fast-tracks it. Wouldn't this cause the patent office to (erroneously) issue a patent to the second person?

To which my attorney replied -

You raise a good point. The fast-tracked application would likely be erroneously granted (unless the other application is published in time to show up in USPTO searches).

The way to address this under the currently in effect first to invent US Patent Law is for the first inventor to provoke an interference proceeding within one year of the issuance of the erroneously granted patent; however, interference proceedings can be very costly.

What a mess.

The workaround

The good news is that there appears to be a simple workaround.

Another option to consider (...) would be to request early publication of your patent application.

This approach simply requires payment of the $300 publication fee earlier in the examination process rather than at the end concurrently with the patent issue fee.

The early publication would make it more likely that your patent application would be cited as prior art against a potential competitive patent application on the fast track.

This is exactly what we did. The USPTO should have the application published within 3 to 4 months.

[swapped]

Please confirm your email address

Just a quick post to share something that seems obvious in retrospect, but took a while to notice and fix.

A mailing list for those wanting to follow Bvckup and Bvckup 2 progress has been up and active over a year now. Subscribing to the list triggers a typical confirmation email with a link that needs to be clicked on. The odd thing was that a good half of those subscribed never bothered to do that.

So last month, after receiving a small rush of sign-ups from Beta List I decided to put things in order and run a bit of A/B testing. Good thing I did.

Simply changing the email subject from this

to this

increased the number of completed subscriptions from 51% to 82%.

The original subject read like... well... a confirmation rather than something that requested an action and people simply did not bother even opening an email. A simple but costly oversight that took me almost two years to realize.

Comments? There is a thread for that:

Hacker News

Reddit

Habrhabr (in Russian)

This is re-post from Bvckup blog. The original is here.