May 23, 2010

Using Amazon's Mechanical Turk for Price Comparison Shopping

I use a ReadyNAS NV attached to my home network.  When I bought the device, I initially installed 3x 300GB drives into it and that has served me well providing 600GB of RAID protected storage.

I recently decided to upgrade the drives.  Netgear has a ReadyNAS Compatibility Guide which lists specifically tested and recommended drives to use with each of the ReadyNAS products.  I knew that I wanted 1TB drives, which seemed from limited research to be a fairly good spot in the market.  That left me with 11 drives to choose from, which seemed like alot of work to research and price compare.  I researched a few on Amazon and bought my first drive for around $145.

For the other 3, I decided to try a different approach mostly as an experiment.  I created an account on Mechanical Turk and asked 3 workers to find me the lowest price they could on any of these drives.  I charged the task out at $3/worker and since there was no clear success criteria, I promised in the task description to give a $10 bonus to whichever worker found the cheapest price.  I mentioned that coupon codes, discounts, and rebates were all fair game, but not to worry about shipping/taxes to keep it simple.  I only cared about price: performance didn't matter much since it was a NAS drive.  Total cost = $3 x 3 + 0.30 x 3 (Amazon's fee) + $10 = $19.90.

Here are the results, about an hour later:
  1. Seagate Barracuda LP ST31000520AS at for £68.02.  I didn't specify US, my mistake.  Still approved the work.
  2. Seagate Barracuda ST31000528AS at for $68.84.  This worker actually listed lowest prices for every one of the drives.  The $68.84 one was the cheapest before shipping/taxes.  This worker got the bonus by a slim slim margin (see worker 3).
  3. Seagate Barracuda LP ST31000520AS at Newegg for $69.99.  This drive ended up cheapest after shipping/taxes.
Ultimately I went with worker #3's suggestion, despite awarding the bonus to worker #2.  Either way, I saved about $75 per drive over what I had bought with my own poor research, so this paid off in spades.  I might have been able to figure this out myself and save the $20 as well, but this approach was less work and more interesting.

I think if I did it again, I'd be a little bit more specific about what I want (US retailer), maybe add shipping/tax to the mix, possibly ask for the 2-3 cheapest drives they could find so I have some choices.  I'd also probably drop the task price to say $0.25 but add that any worker that gets within 10% of the lowest price worker will also earn a $3-5 bonus.  I suspect that the ability to earn $3 for a few quick pricegrabber searches might make sticking around and spending more time doing research less enticing.  Still the results weren't that bad with my first try, enough to make me wonder what else I could use the turk workers for.

Google Encrypted Search

It's often fun to read the response that the internet community has to Google's launches, especially ones that I'm somewhat familiar with.  There is always a bit of tinfoil hat concerns about Google's intentions.

Late last week we launched to Beta an Encrypted Google Search option.  Most discussions focus on the privacy aspect of this launch, but there are a number of discussions noting that this disables referrer (and hence query) passing for many destination websites: take the webmasterworld discussion for one example.  The tin foil hat interpretation is that Google hidden agenda is to prevent webmasters from seeing their query data.

Fortunately, it's easy to see what is actually going on.  When you surf using the HTTPS protocol, the goal is to encrypt(hide) your surfing traffic from your transmitting network, not from the destination sites.  However, if you click from a HTTPS page to an HTTP page, passing the referrer would leak a small amount of data about your encrypted traffic to the network.  As a result, all web browsers that I know of send an empty referrer string in this case.  Interestingly, if you navigate between HTTPS pages, even on different domains, the referrer is passed.  This is consistent with hiding the data from the network but not the destination site.

If a webmaster so desired, they could move their entire site onto HTTPS and then start getting the HTTPS referrers sent to their server again.  If Google's intent was to prevent websites from seeing query strings, there are much easier ways to do so, such as using POST.

May 22, 2010

Gas Station Inefficiency

Near where I live is a gas station that is almost always packed and overflowing into the road. It's not particularly small, but they have decent prices.

I've wondered why the station always looks so busy. I think I have the answer. In addition to having decent prices on gas, they also have a big sign that reads "9c/gallon off with cash". I've observed that the vast majority of the users wait in line until their car is in front of a pump, then walk into the store to get in another line to prepay in cash for their gas. Once they've prepaid, they return, pump, and sometimes go back in for change. If you add all this up, they spend about 5-10 minutes with their car in front of the pump for every 1 minute or so of actual pumping of gas.Pump utilization is abysmal, leading to low throughput, leading to long queues. Sounds like a dumb algorithm to me.

What I don't know is if this behavior increases their sales or decreases them. I know that Cristin and I sometimes avoid this station because of the congestion meaning lost sales. However, it's possible that the lines of overflowing cars out into the road draws attention and gives a false sense that this must be the cheapest around driving more sales still.

May 10, 2010

Henry Coe, Kelly Lake, Backpacking

This past weekend I went backpacking in Henry Coe with JeremyShapiro, Matt Cutts, and David Signoff.

We hiked in on a perfect day from the Hunting Hollow entrance on a gorgeous day, a grueling climb up Middle Steer Ridge Trail, a short stroll along Steer Ridge Road to lunch at Wilson Peak where we saw a deer also relaxing and having lunch. We backtracked slightly and quickly descended half the elevation we just gained down Serpentine Trail. Back up on Tule Pond Trail, following the ridge on Wasno Road, then Wagon Road, and then a very steep descent down Kelly Lake Trail to Kelly Lake. Total distance: roughly 10 miles

There were 4 parties including ourselves overnighting at Kelly Lake. Beautiful spot, but lacking for ideal campsites and we weren't the first to arrive. I think I still prefer having Redfern pond to myself 2 years ago to sharing Kelly Lake with others. Serenaded by birds and then frogs, our crew played cards and then got a good nights' sleep.

The next morning, rain clouds started appearing so we packed up camp quickly and headed out. Our plan was to stick to trails back to Hunting Hollow, but we hit some moderate rain on the return hike and so took a shortcut. Back up Kelly Lake Trail on the other side, ridge walking on Wasno Road until descending on Dexter Trail which is when the rain hit, and then a moderate descent along Grizzly Gulch Trail until we reached the Coyote Creek park entrance. From there, only a 2 mile flat walk back to Hunting Hollow Entrance where my car was getting a nice shower. Total distance: roughly 7 miles.

I found a similar hike done by another crew, with GPS map and altitude here: Hunting Hollow to Kelly Lake round trip with GPS. That trip was 20 miles with 6800ft of elevation gain/loss.