Implementing features is hard!

We’ve been quiet for a while now but we’d like to stress that this isn’t because we’ve stopped working – quite the opposite! Instead, we have been working on new features for out January 1st 2012 launch.

Today was the first day that we rolled out the new features to our closed beta users. (A “closed beta” is simply a beta test with a few hand-selected users who are happy to use a site full of bugs.)

This is a fairly significant milestone in terms of the site – our “core launch” features are actually live and running right now and it looks like we will be “feature complete” (that is, only working on bugfixes) by the 23rd of December. This is the day that we will open up our public beta to those users who signed up (link is on the front page).

The initial features are fairly simple – users are able to track their own collections along with trades and new additions and to see the price of their collections over time.

In addition, users can see how things like the 2011 World championships affected the price of single cards or their entire collection.

Additionally, users will be able to create decklists and share them with anyone interested, and again, these lists will show historical prices over time so you can see how different events impacted the price of various cards.

The decklists will show users who are logged in the cards they are mising and we have set up one-click ordering of only the cards that you still need to finish your deck at the lowest prices around.

We also allow users to log trades via the wizard that we released earlier (it now has a new look) – this will let you determine if you consistently make good trades over time and should let you keep your collection up to date more easily.

Lots of cleanup has also been added, including (finally!) access to foil card prices. We’ve always been gathering these prices, so you should have several months of data to peruse when the feature goes live on January 1st.

Alerts have also been added. These alerts are user-configurable and can be set up to tell you if any card is selling below a specific threshold price, a percentage below the “Fair Trade Price” or is significantly trending up or down. It’s also possible to view lists of cards sorted by recent gains and losses and those cards that are selling significantly below their typical price at a specific vendor.

The features above, while fun, are just the beginning – we’ll be rolling out at least one significant new feature every 2 weeks for the forseeable future. Our goal is, and always has been, to build a site with the fastest, most reliable MTG card prices around and to give players the tools to use this data effectively.

Look for more blog posts with further details and sign up for the beta if you haven’t already!

Finding a “Fair Trade Price” for a card

At our goal is to always show how much a “fair” price is for a given card. To do this, we gather prices from all over the Internet and show them, along with their history, on our card pages.

We noticed a serious outlier today with the “average” prices – several cards had been input incorrectly by a single store and this skewed the average price of all cards significantly. To avoid this occurring in the future, we’ve decided to implement a new version of Fair Trade Price beginning with updates tomorrow.

The new algorithm works as follows:

We aim to find prices of cards that have been sold recently. “Recently” is highly dependent on the card itself – Black Lotus typically change hands less frequently than a play-set of lightning bolts, for example. It’s important to get a value for how much a card sells for, not how much it is listed for. I can list 500 Lightning Bolt’s for $1000 each on Ebay but unless someone buys them, this price is irrelevant. Our algorithm therefore is essentially a weighted average of the current prices at various stores, weighted by the number of sales those stores typically have.

How do we know how many cards a given store sells? We don’t, not really, but we can guess based on the inventory levels that the stores publish. We’ve been collecting inventory information from all the big stores plus Ebay, amazon and all the stores for over a month now and we feel fairly confident in our initial ranking of weights.

We normalized the weights so that Ebay count’s as a multiplier of 1. Our first attempt at weighting sales is as follows:

Ebay x1

Starcity x0.84

ABUGames x0.64

MTGMintCard x0.22

TCGPlayer LOW x1.12

As we add in other stores and update our data, these weights will change. We will update all weightings on the 1st of every month to show how important each vendor is in our index.

How do these weights work? An example:

Liliana of the Veil is currently (11/20/2011 at noon) listed for:

Ebay - $35.62
Starcity - $39.99
ABUGames - $47.99
MtgMintCard - $52.99
TCGPlayer LOW - $32.13

The calculation that we do is as follows:

((35.62*1) +(39.99*0.84) + (47.99*0.64) + (52.99*0.22) + (32.13*1.12))/(1+0.84+0.64+0.22+1.12)

= $38.63 Fair Trade Value

This calculation will start being used on all cards starting tomorrow – we’re just running the final tests now to ensure we catch all the outliers and bad data before it comes into the calculation. Specifically, we throw away any single event that is more than 3 standard deviations away from the mean, unless there is more than 1 such occurrence. Later, we plan on using (stat’s geek alert!) Chauvenet’s criterion to detect outliers instead.

We want our prices to be the fastest and most accurate on the web. If you have any comments on how we plan to do things, or just want to say hello we can be contacted at or on Twitter or Facebook, or post in the comments section below.


Olivia Voldoren Spikes from $5 to $15 in a day because of Chopin’s MTG Worlds Deck!

Tweet showing Chopin's deck may cause a price spike of Olivia Voldaren

It looks like our data that was pointing to a big spike in the price of Olivia Voldoren were right – she went from being a $5 card to a $15 card in less than a day on the back of Patrick Chopin’s MTG Worlds decklist.

A guide to the deck can be found here:!

Or for those of you who prefer text, here is the full deck list:

3 Olivia Voldaren
3 Snapcaster Mage
2 Precursor Golem

1 Wurmcoil Engine

1 Inferno Titan
3 Liliana of the Veil
3 Mana Leak
2 Galvanic Blast
4 Forbidden Alchemy
3 Slagstorm
1 Devil’s Play
4 Desperate Ravings
1 Go for the Throat
1 Ratchet Bomb
2 Doom Blade

4 Darkslick Shores
1 Copperline Gorge
4 Blackcleave Cliffs
1 Rootbound Crag
2 Drowned Catacomb
5 Mountain
3 Swamp
1 Island
1 Shimmering Grotto
4 Sulfur Falls

2 Ancient Grudge
1 Geistflame
1 Slagstorm
1 Mimic Vat
2 Curse of Death’s Hold
2 Surgical Extraction
1 Wurmcoil Engine
1 Flashfreeze
1 Negate
1 Mana Leak
1 Dissipate
1 Galvanic Blast

If you’re interested in getting news of other spikes before they happen, sign up for the beta test here

The beta starts on December 1st and will let users learn of upcoming shifts in the trading landscape before anyone else knows about them, allowing users to act quickly to snap up the cheapest cards before they are gone then flip them for serious profit.

Trading at the MTG World Championships

Planning on doing some serious trading at mtgworlds? Read this quick guide to make sure you get what you need!

1. Figure out what you want before you start trading

Our biggest trading tip is to know what you want before you start. If you’re looking to build a standard deck, make a list of exactly which cards you need and try to stick to that list while trading. Just because someone has a foil Snapcaster Mage doesn’t mean that you should trade for it if you’re looking for 4 of something else.

2. Make sure you know what cards are worth

Once you know what you are  looking for, it’s important that you don’t get conned out of your best cards. At big events like worlds, almost everyone is friendly but a few are very aware of the fact that they won’t see the people they trade with again and act like sharks. It’s a good idea to use the MTG Card Search either on a laptop or (ideally) on a smartphone so you can see how much various stores charge for a given card.

For more complex trades, we strongly advise using the MTG Fair Trade Wizard to automatically price cards as you add and remove them from the trade.

3. Check the condition

Most prices are for “mint” cards – that’s cards that have never been played with, or only very lightly played in sleeves. If the card you are trading for isn’t mint, be sure to point this out and use it to your advantage – ask for more in return.

4. Know how to spot a fake – especially on older cards

Older cards are both valuable and easy to fake. Look carefully at any card over $20 or so in value – does it feel like a regular card? Does it bend correctly? Are the Colors looking good? Is the border correctly colored? If you’re not sure or feel uneasy, just walk away.

5. Trade up!

In general, it’s better to trade several low value cards for a single high value card. High value mythics and older rares tend to hold their values for longer periods of time (and even increase) whereas lesser cards are typically forgotten when they rotate out of the current tournament block.

6. Know what is rotating in (and out!)

Speaking of the current tournament block, pay attention to what is coming up in the next few months. Standard-powerhouse cards that were once worth a lot of money may be underpowered for Modern and so will see a significant price drop. Try to dump these cards and pick up similarly-prices cards from Innistrad instead.

We hope this short guide helps you with your trading at mtgworlds. If you make an especially great trade, or simply want to vent, feel free to post below.