Justifying the small size of a dataset due to collection difficulties I'm working in an empirical field and have recently had a paper about a data collection effort and subsequent analysis thereof which was provisionally accepted, conditional on revisions. The negative remark most difficult to address is that the dataset I acquired was considered relatively small; How can I justify the small size of the dataset in a sound manner due to practical difficulties in acquiring data?

It is not possible for me to collect any more data in terms of money, manpower or even time... which all add up to more or less to "research capital". I have seen other datasets used which are not much bigger, but there are also corpora which are bigger by a significant margin. Likewise, some datasets are quite similar while others are completely unrelated to mine. Finally, while some corpora are freely available, for the majority of the papers in my field, it is quite rare for publications to explicitly state how one can acquire the data for their own purposes, and so the actual ability to even aquire data second-hand seems to be spotty.

Basically, I would need to reformulate the paragraph above into some form which I can put into the paper which needs revision; What can I do?
As has been said, a satistical analysis of your data set will clarify with how much confidence and accuracy you can  conclude your findings. This an essential part of the scentific process

In the natural sciences particularly, data collection can be problematic and limited by time and budget,  but the community are aware of this, as should be your reviewer. 

All that is required is that you report your findings appropriately  even if you don't necessarily like the answer! In extreme circumstances you may have data sets that are so scant or varied you simply do need more work. It happens.

Science progresses with knowledge which includes less than optimal data,  as does helping those that come after you do better by explaining in your paper how you could improve your own approach. 

I agree the reviewer is probably asking for this kind of analysis and not why you were unable to do as much work as you would have liked