1. English correction corpora
David Ling

2. Correction corpora Training data: Corpus name No. of correct sentences
No. of problematic sentences
Lang8
533316
514077
Nucle
26972
16039
Proofreading exercise 42
FCE
12359
17139
Potential corpus:
WikiED -- A Corpus of Corrective Wikipedia Edits (very large but noisy)

3. Lang8
A social networking service (Japan) for learners of foreign languages
Crawled in 2012
Example sentences
Original: But it 's a exam week now . . .
Edited: But it 's exam week now . . .
Original : I try my best either study and Track & Field
Edited: I will try my best for both study and Track & Field
Original : Diet is difficult .
Edited: Diet is difficult .

4. Nucle Students’ scripts from Singapore More advanced, longer sentences
Example sentences
Original:
These computer simulations take significantly shorter time hence it is a preferred choice as it means that the product can be sold in the market in a shorter period of time .
Edited:
These computer simulations take significantly shorter time ; hence , they are a preferred choice as it means that the product can be sold in the market in a shorter period of time .
If the former need is put forward to an engineer , he can view it as a broad topic with many possible solutions .
If the need of feeding millions of starving people is put forward to an engineer , he can view it as a broad topic with many possible solutions .

5. FCE
Exam scripts written by candidates sitting the Cambridge ESOL First Certificate in English
Examples:
Original:
Famous people deserve to have freedom to do whatever they want , but it is quite difficult to do thing in a public places , because nobody like famous politicians or film stars without asking questions .
Edited:
Famous people deserve to have freedom to do whatever they want , but it is quite difficult to do things in public places , because nobody likes seeing famous politicians or film stars without asking questions .
When I said to my mother , she asked me not to do it again .
When I told my mother , she asked me not to do it again .

6. Exam Proofreading exercises
Exam exercises for Hong Kong students

7. Sentences in training data
Transformer, 8k vocab(subword), 8000 steps
In: But it 's a exam week now
Out: But it 's a exam now now .
Ref: But it 's a exam week now
hparams = transformer.transformer_base()
hparams.num_hidden_layers = 2
hparams.hidden_size = 128
hparams.filter_size = 512
hparams.num_heads = 4
hparams.attention_dropout = 0.6
hparams.layer_prepostprocess_dropout = 0.6
hparams.learning_rate = 0.05

8. Sentences in training data
8k vocab , steps
original, edited, reference:
however , I hoped rain because it is too hot .
however , I hope rain because it is too hot .
However , I hoped it would rain today because it is too hot .
Actually I keep watching it these days .
Actually I watch it a lot these days .
But it 's a exam week now
But it 's a exam now .