Frequently Asked Questions

If you have a question that is not answered on this page, please send it to the Zyzzyva Users mailing list. There are many users on that list who generally respond quickly and helpfully to most questions. Additionally, full online help documentation for the latest version of Zyzzyva can be found here.

Most of these answers were written in the first person by the original Zyzzyva author, Michael Thelen.

Why is the program called Zyzzyva?

I wanted to pick a fun word that was somewhat unique. I knew "zyzzyva" was one of the most improbable words to be played in a SCRABBLE® game, and I liked the sound of it. Later on, after I had picked the name, I realized that since "zyzzyva" was also the last word in alphabetical order (it has since been replaced by "zzz"), I could call Zyzzyva "the last word" in word study. I wish I could say I was smart enough to come up with that slogan from the start.

Why is NASPA involved with Zyzzyva?

With the release of the OTCWL2014 and OSPD5 lexicons in 2014, Hasbro, Inc. began stronger enforcement of their copyrights on the word lists. This entailed a license agreement that would bind the licensee (Michael Thelen's Boshvark Software, LLC) to prevent the leakage of those lists, which had theretofore been a part of the Zyzzyva distribution. As a result, he decided to sell the product to NASPA, and the new NASPA Zyzzyva Committee began work to change the product so that it would comply with the terms of license, and to tie its availability to NASPA membership.

Why is Zyzzyva available for free?

I created Zyzzyva because I wanted a program for studying SCRABBLE® words. There are several programs available, but all of them either lack features I wanted or do not run on Linux. I therefore took it upon myself to create the program I wanted, and Zyzzyva is the result. I have made it available under the GNU GPL because I feel that others should be able to benefit freely from my work. [Note: Following Zyzzyva's purchase by NASPA, the open-source Zyzzyva distribution is now distributed only under the GNU Lesser GPL (LGPL) version 2.1, which retains some open-source privileges but also allows NASPA to build the proprietary NASPA Zyzzyva on top of the Zyzzyva code-base.]

What is NASPA Zyzzyva and who can use it?

NASPA Zyzzyva is the same program as the "free" Zyzzyva, with some code added and operational restrictions imposed to comply with the terms of license for the new, protected lexicons. NASPA Zyzzyva is intended for use by NASPA members as a benefit of membership, while Zyzzyva is freely distributed and does not include the protected lexicons or the means to work with them, as they are securely encrypted in the NASPA Zyzzyva distribution. The main operational restriction on NASPA Zyzzyva is that users can export at most 200 words to a text file at one time.

When will there be a version of Zyzzyva for my handheld device?

The Zyzzyva iPhone app is now available in the App Store! There is also a free Zyzzyva Lite app, which includes only search and judge functions. There are currently vague hopes, but no actual plans, to create Zyzzyva apps for other handheld devices.

How can I transfer my Zyzzyva data from one computer to another?

You can transfer all your data to a new computer by copying your data directory. You can find out where your Zyzzyva data directory is by opening the Preferences window in Zyzzyva and looking at the Data Directory setting. Make a copy of this directory, and move it to wherever you like, on the new computer. Then, after you install Zyzzyva on the new computer, open the Preferences window and change the Data Directory setting to point to wherever you put your data directory from the original computer.

The transfer should work regardless of the operating systems used on the two computers. For example, you should be able to transfer your data directory from a Windows computer to a Mac, or vice versa.

Can I keep my Zyzzyva data on a USB thumb drive?

Absolutely. This may be a good option for anyone wanting to use Zyzzyva on multiple computers without having to copy data directories back and forth. Simply copy your data directory onto the USB drive (using the process described in How can I transfer my Zyzzyva data from one computer to another?). Then open the Preferences window and change the Data Directory setting to point to the data directory on the USB drive.

How do I print a list of words?

Unfortunately there's no print functionality built into Zyzzyva yet. The best you can do for right now is right-click (Control-click on a Mac) on any word list (e.g. Search results) and save it in plain text format. Then manipulate the list and print it from a text editor program, like Notepad or Wordpad on Windows.

How does the Cardbox system work?

The basic idea is that you must first tell Zyzzyva which words you'd like it to keep track of. You generally do this by performing a search, then right-clicking the search results and choosing "Add to Cardbox". Then Zyzzyva keeps track of those words and automatically quizzes you on the ones it thinks you need to see each day. When you miss a word frequently, Zyzzyva will show it to you more often. A more detailed explanation is given in the Help documentation.

When viewing search results, what are the '-' marks at the beginning or end of certain words?

Those marks denote "inner hooks" - they mean that either the first or last letter of the word can be dropped to form another valid word, depending on where the hyphen appears. If the hyphen appears at the beginning of the word, then the first letter can be dropped. If the hyphen appears at the end of the word, then the last letter can be dropped. A more detailed explanation is given in the Help documentation.

How does Zyzzyva calculate the probability of a word?

I don't have a nice formula handy, but it's basically a straight calculation of the number of possible combinations to get a particular set of letters from a full bag, including blanks. Separate combination values are calculated for drawing zero, one, or two blanks, and then the numbers of combinations are added together to get the total number of ways of drawing a word. If you're interested, you can see the source code for yourself here (see LetterBag::getNumCombinations particularly).

Are you sure the probability calculation is accurate? It seems unintuitive to me.

Yep, it really is correct. The calculation of probability is notorious for violating human intuition. One useful guideline to remember is that doubled or tripled letters make a particular letter combination much more improbable than you might think. That's because the number of ways to draw two identical letters out of the bag is generally much lower than the number of ways to draw two different letters out of the bag. If you'd like to verify the math, you can see the source code for yourself here (see LetterBag::getNumCombinations particularly).

Are you really sure about the probabilities? I need to see more examples.

Consider BAILERS versus BELIERS. BAILERS is a fair amount more probable than BELIERS because of the doubled E's. However, it seems intuitive to say, "If BEILRS has been drawn from a full bag, then there are 9 A's and 11 E's in the remaining pool. The E is the more likely draw, which means BELIERS should be more probable than BAILERS."

While it is true that drawing a single E is more likely than drawing a single A, the math for calculating the probability of a word is more complicated than that. You can't just start calculating with the assumption that BEILRS has been drawn; those letters themselves factor into the calculation, and they are not independent events. In this case, we can reduce the difference between BAILERS and BELIERS to the difference between drawing AE or EE when drawing two tiles from the bag.

If you draw two tiles out of a full bag, the probability of drawing two E's is much lower than the probability of drawing an A and an E. That is because there are 9 x 12 = 108 ways to draw an A and an E if you draw two tiles. But there are only (12 x 11) / 2 = 66 ways to draw two E's if you draw two tiles. This number of combinations is called "12 choose 2", and is explained in more detail in this
Wikipedia article about combinations.

To reduce this to a simple example where it's easy to enumerate all the possibilities, consider a 4-tile bag containing only AAEE. I'll label the tiles A1, A2, E1, E2 for convenience. There are 6 possible ways to draw two unordered tiles:

A1 A2 = AA
A1 E1 = AE
A1 E2 = AE
A2 E1 = AE
A2 E2 = AE
E1 E2 = EE

As you can see, AE is drawn 4/6 times, while AA is drawn only 1/6, and EE is drawn only 1/6 as well. Even though A and E are equally likely to be drawn if you are only drawing one tile, if you're drawing two tiles it is much more likely to draw one of each than to draw duplicates.

As another example, consider a bag where E is more likely than A, as is the case in the full Scrabble bag. Consider a 6-tile bag containing AAEEEE, with tiles labeled A1, A2, E1, E2, E3, E4. There are 15 possible ways to draw two unordered tiles:

A1 A2 = AA
A1 E1 = AE
A1 E2 = AE
A1 E3 = AE
A1 E4 = AE
A2 E1 = AE
A2 E2 = AE
A2 E3 = AE
A2 E4 = AE
E1 E2 = EE
E1 E3 = EE
E1 E4 = EE
E2 E3 = EE
E2 E4 = EE
E3 E4 = EE

AA occurs 1/15 times, AE occurs 8/15 times, EE occurs 6/15 times. Even though E is twice as likely as A, AE is still more likely than EE! This is the same basic principle that also causes words with duplicate letters to be drawn with lower probability from a full Scrabble bag.

Complicating the math even further is the fact that Zyzzyva calculates probabilities using a full 100-tile bag including two blanks. That may account for differences (usually minor) with other probabilities you may have seen calculated elsewhere, many of which use a 98-tile bag with no blanks.

Why did Zyzzyva mark all my answers as missed when I actually got them all correct?

Zyzzyva only marks all responses as missed if you actually entered all the correct responses, but also provided an incorrect response. The reason for marking all responses as missed is because (currently) Zyzzyva has no other way of marking the question as missed without marking at least one response as missed. So instead of picking a random response to mark as missed, it marks them all.

This only happens if you have the 'Mark question as missed after an incorrect response' setting activated, but not 'End question after an incorrect response'. Technically, it could also happen if you have the 'End question after an incorrect response' setting activated, but not 'End question after all correct responses', and the incorrect response is the last one you give.

You can find the Zyzzyva issue tracker item for this issue here.

I love Zyzzyva so much that I would like to send you giant piles of money. How can I do that?

Michael Thelen originally wrote: That is so nice of you! I'm always very happy to receive donations of any amount.

NASPA writes: If you are feeling philanthropic, why not consider a donation to our Foundation for Youth Literacy?


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