The phrase "a voluntary base" is correct and usable in written English.
It can be used in contexts where you are referring to a foundation or starting point that is based on voluntary participation or consent.
Example: "The organization operates on a voluntary base, encouraging community members to contribute as they see fit."
Alternatives: "a voluntary foundation" or "a voluntary framework".
A participatory sensing approach for crowd monitoring faces a major limitation: Participation is based on a voluntary base.
Scala did so in order to avoid even any appearance of a potential conflicted of interest situation and simply as a precautionary measure on a voluntary base.
Half of the programmes offered in Europe are voluntary ones [7], whereby the mode of voluntary participation must be seen with caution as offenders are often "forced to participate on a voluntary base" in order to avoid further negative sanctions or measures.
All subjects participate on a voluntary base and receive a small financial compensation (50 euro and travel expenses).
MDGs were agreed on a voluntary base by governments; the new goals should be norms for global governance and to reinforce the concept of the 'right to health'.
Owners and other human house mates of dogs with VL residing in the Netherlands were asked to participate on a voluntary base in this investigation.
In fact, a voluntary based access instead of a systematic one may have selected those patients with higher prevalence of symptoms and it may explain the higher HPV prevalence observed.
One of the major limitations to this study population is selected on a voluntary basis based on one area elderly population screened, which would potentially introduce selection bias.
The application of the ECBM should be on a voluntary basis based on a case-by-case assessment of the MS. (c) the legal protection of persons resident in a cross-border region with regard to the Mechanism.
Chimpanzees are therefore more likely to help others upon recipient's request than on a voluntary basis or based on short-term reciprocity.
Recruitment was based on a voluntary basis and events took place in 12 regions out of 22 in metropolitan France (Alsace, Aquitaine, Bretagne, Bourgogne, Champagne-Ardenne, Ile-de-France, Langedoc-Roussillon, Midi-Pyrénées, Nord-Pas-de-Calais, Pays de la Loire and Rhône-Alpes).
