The phrase "are collected mainly" is correct and usable in written English.
It can be used when discussing the primary method or source of collection for data or information.
Example: "The survey responses are collected mainly from online participants to ensure a diverse range of opinions."
Alternatives: "are primarily gathered" or "are chiefly collected".
This variable is expected to positively or negatively influence the respondent NTFPs collection from FGR especially for those products that are collected mainly for sale.
The data are collected mainly by NaruInsight monitoring devices, which analyse traffic at choke points on the internet.
Data are collected mainly by interviews, documents, and observations.
In this work, H. sapiens intra-species PPIs are collected mainly from three databases, MINT [ 15], BioGRID [ 16], and IntAct [ 17].
If however HBM data are collected mainly for the purpose of aetiologic research, this may lead to an emphasis of extending large-scale epidemiological studies (often initiated in other contexts) at the expense of studies into locally relevant exposure pathways.
Since radiation damage can be reduced in cryo-temperatures [ 56] and the preserved samples can maintain their close to native structures, the data sets for structural determination are collected mainly from cryo-samples, if possible.
Castles were built and taxes were collected, mainly in furs and, later, in grain, butter, and money.
Blister beetle (family Meloidae), any of approximately 2,500 species of beetles (insect order Coleoptera) that secrete an irritating substance, cantharidin, which is collected mainly from Mylabris and the European species Lytta vesicatoria, commonly called Spanish fly.
Thus, the data for this study was collected mainly in that area.
At that time fish stocks were abundant and revenue was collected mainly from land.
Bathymetric and magnetic data were collected mainly in the Palau Basin during the R/V Yokosuka YK10-14 cruise.
