"The model is quantized to 8 bits per parameter and evaluated using BF16 floating point numbers" means the model is stored as 1 byte per parameter even though it's using a 2 byte type during compute. This is backed up by checking the size of from the download which comes out as 171,363,973 bytes for the model file.
> and was probably trained on the test data
This is likely a safe assumption (enwik8 is the default training set for RWKV and no mention of using other data was given) however:
> No one would be impressed with saving 78 MB on compression using a 340 MB dictionary so I am not sure why this is good?
The Ts_zip+enwik9 size comes out to less than the 197,368,568 for xz+enwik9 listed in the Large Text Compression Benchmark despite the large model file. Getting 20,929,618 total bytes smaller while keeping a good runtime speed is not bad and puts it decently high in the list (even when sorted by total size) despite the difference in approach. Keep in mind the top entry at 107,261,318 total bytes in the table is nncp by the same author (neural net but not LLM based) so it makes sense to keep an open mind as to why they thought this would be worth publishing.