Below some results running the "Book Stack" test written by Alexey Lubkin. [1]

The test were run in comparison of zx8 (ps) to either RC4 or ZK-Crypt.
In order to verify the correctness of the implementation in general and
the results produced by zx8 (ps) an implementation of RC4 is included
and the test runs produce the expected results for RC4 as describe in
the paper
- The experimental distinguishing attack on RC4 - [2]


Code:
# Comparing zx8 against RC4

Table 1:
--------
Number of files generated by zx8 and recognized as non-random (from 100)
Test run with the book stack parameter  "-w 16 -u 16 -q"

 zx8 (ps)
+--------------------------------------------------------------------------+
|Length(bit)|2**31 |2**32 |2**33 |2**34 |2**35 |2**36 |2**37 |2**38 |2**39 |
+--------------------------------------------------------------------------+
|Non-random |    9 |    9 |    9 |    9 |    9 |    6 |    5 |    5 |    6 |
+--------------------------------------------------------------------------+


Table 2: 
--------
Number of files generated by RC4 and recognized as non-random (from 100)
Test run with the book stack parameter  "-w 16 -u 16 -q"

 RC4
+--------------------------------------------------------------------------+
|Length(bit)|2**31 |2**32 |2**33 |2**34 |2**35 |2**36 |2**37 |2**38 |2**39 |
+--------------------------------------------------------------------------+
|Non-random |    4 |    6 |   10 |   23 |   44 |   70 |   98 |   99 |  100 |
+--------------------------------------------------------------------------+




# Comparing zx8 against ZK-Crypt

Table 3: 
--------
Number of files generated by zx8 and recognized as non-random (from 100)
Test run with the book stack parameter  "-w 32 -u 65536 -q"

 zx8 (ps)
+-------------------------------------------------------------------+
|Length(bit)|2**24 |2**26 |2**28 |2**30 |2**31 |2**32 |2**33 |2**34 |
+-------------------------------------------------------------------+
|Non-random |    1 |    3 |    4 |    7 |    5 |    7 |    8 |    4 |
+-------------------------------------------------------------------+



Table 4:
--------
Number of files generated by ZK-Crypt and recognized as non-random (from 100)
This test had used the book stack parameter  "-w 32 -u 65536 -q" 
Parameters and results of ZK-Crypt as described in [3]

 ZK-Crypt
+-------------------------------------------------------------------+
|Length(bit)|2**24 |2**26 |2**28 |2**30 |2**31 |2**32 |2**33 |2**34 |
+-------------------------------------------------------------------+
|Non-random |   25 |   51 |   97 |  100 |  n/t |  n/t |  n/t |  n/t |
+-------------------------------------------------------------------+
 [ n/t = not tested ]
The source code for running these tests and some test results can be downloaded here
http://www.freecx.co.uk/zx8/bookstack/




The book stack test itself is written by Alexey Lubkin
http://web.ict.nsc.ru/~ldp/download.html


References:
-----------

[1] - On ZK-Crypt, Book Stack, and Statistical Tests -
Doroshenko, Fionov, Lubki, Monarev, Ryabko
http://eprint.iacr.org/2006/196

[2] - The experimental distinguishing attack on RC4 -
Doroshenko, S. and Ryabko, B. (2006)
http://eprint.iacr.org/2006/070

[3] - The distinguishing attack on ZK-Crypt cipher -
by Alexey Lubkin and Boris Ryabko
http://www.ecrypt.eu.org/stream/papersdir/076.pdf