I think that in general (not just for Vietnam) a few important distinctions can be made between family farms and rural households. Rural households need not necessarily be involved in farming: they might not own land, but may be hired as labourers by family farms. Often their sources of income are crafts or urban employment (construction, taxi-driver etc).

Thanks Gerdien. in many aspects, I share your opinion. But my question appeared, because in the literature on Vietnam only households are mentioned, without any reference to family farms. Therefore I suppose that family farms and rural households are identical terms in case of Vietnam, although I am not 100% sure. Also, theoretically it is not necessay that farms owning land: in the literature review worldwide we have the notion of "landless farmer". This is in the context that access to land cannot be considered a relevant criteria of attributing a rural family to family farm or not.

Actually, in Vietnam as in China, there are lots of "non agricultural enterprises" in the countryside. It is sometimes difficult to know if the households can be classified as "family farms" or not, because these households often favor poly-activity in order to lower risks. I don't know enough about statistics in Vietnam, but you should be able to find statistics for rural households on one hand, and type of activities on the other. The statistics may be collected in different books and are not necessarily compatible. Often, a fieldwork and good networks with local authorities can help to sort out that type of difficulties (this is at least the experience I had in China). Hope this helps.

Thanks Louis. Actually, the best statistical sources for me would me agricultural census. As it is impossible to get access to its primary data, the only alternative solution would be Living Standard Measurement Study data (VHLS/LSMS). The problem is that it is focused on households and not farms. In this context, I agree with you that it is necessary to distinguish rural households operating in agriculture from total rural households. A careful and thorough investigation of LSMS questionnaire is necessary for this purpose.

In the German village that I call my hometown, you would get very different answers depending how you frame your question. Around the built-up core of the village you find isolated farm buildings surrounded by meadows, fields and forests. Several of these farms do not house farming households, but commuters with jobs in far-away cities, or hospitality enterprises (hotel; B&B; party facilities). Other farm (buildings) are home to a farming household (or at least one person full-time farming). The farmer is likely to own the building and some of the surrounding land (s)he farms, but most probably leases additional land from non-farming neighbors or other land owners (e.g. church). Within the built-up area of the village (would be considered to be a small town in Africa) some households own a parcel out in the rural area of the village that the owner cultivates through a contractor or as a part-time farmer. In the latter case, on Saturday and after hours of a full-time job. I could tell you similar stories about African villages. In other words, what counts are your definitions. What is a household, what is a farm (agricultural enterprise for x% of its income; spatial unit?), what is a farmer (part-time; full-time; seasonal) and what is rural? For example, you seem to jump from farm to agriculture in your answer. I am not sure many farmers/households would be able or willing to answer your questionnaire in my village.

From your question, I take your research is data driven rather than problem-oriented. May be your question can be better answered if you explain the aim of your research

Hope my story helps to focus your questions.