Shobha Subramanian and Soniya Mahajani in an article in Brand Equity, the supplement to The Economic Times of India, on 16.4.2014 titled "Unfocused But Why?" stated that in many developed markets, private online communities are being used for focus group research.
The private online community consisted of specially recruited consumers, with whom researchers interact, converse and dialogue. The biggest advantage of this method is that members respond at a time and from a place convenient to them. The critical group dynamics is retained since members respond to what others say.
It may be limited to consumers who have internet connectivity. Hence it can have some limitations.