Vocabulary Data of 16 English as a Second Language learners.

Every learner is asked to answer 11,999 English words and 1 pseudo word.

Participants were collected to create this dataset in  January, 2009.  1 Learner is unpaid, and 15 learners are paid.

Most of the participants were Japanese native speaker. Most of the participants were the students of the University of Tokyo.
http://prt.nu/0/vkd

Usage, Terms of Use, and Details are written in the readme.txt in the zip file.

Especially, please remind the following:

As written in the readme.txt, this dataset is for research purpose only and please do not redistribute this dataset.
And please cite the following two papers to use this dataset:

@article{Ehara:2013:PRS:2438653.2438666,
author = {Ehara, Yo and Shimizu, Nobuyuki and Ninomiya, Takashi and
Nakagawa, Hiroshi},
title = {Personalized reading support for second-language web documents},
journal = {ACM Transactions of Intelligent Systems and Technology},
issue_date = {March 2013},
volume = {4},
number = {2},
month = apr,
year = {2013},
issn = {2157-6904},
pages = {31:1–31:19},
articleno = {31},
numpages = {19},
url = {http://doi.acm.org/http://dx.doi.org/10.1145/2438653.2438666},
doi = {http://dx.doi.org/10.1145/2438653.2438666},
acmid = {2438666},
publisher = {ACM},
address = {New York, NY, USA},
keywords = {Reading support, Web pages, glossing systems, item
response theory, logistic regression},
}

@InProceedings{ehara-EtAl:2012:PAPERS,
author    = {Ehara, Yo  and  Sato, Issei  and  Oiwa, Hidekazu  and
Nakagawa, Hiroshi},
title     = {Mining Words in the Minds of Second Language Learners:
Learner-Specific Word Difficulty},
booktitle = {Proceedings of COLING 2012},
month     = {December},
year      = {2012},
address   = {Mumbai, India},
publisher = {The COLING 2012 Organizing Committee},
pages     = {799–814},
url       = {http://www.aclweb.org/anthology/C12-1049}
}

For further details about this dataset,  please contact me (i [atmark] yoehara.com).