I can replicate your problem if I change what semantic term I associate the variable sex with. For example, when I use this semantic term in my dataset: http://id.nlm.nih.gov/mesh/2018/M0446358 (Genotypic Sex)
but I have this semantic term in my sparql query: https://id.nlm.nih.gov/mesh/2018/M0446359.html (Phenotypic Sex),
then I get the empty response you have posted.
Here is the relevant entry in the participants.json:
"sex": {
"label": "",
"description": "sex of the participant as reported by the participant",
"levels": {
"M": "male",
"F": "female"
},
"source_variable": "sex",
"isAbout": {
"url": "http://id.nlm.nih.gov/mesh/2018/M0446358",
"label": "Genotypic Sex"
}
}
which should match the URL referenced in male_subj_IDs.sparql:
# find sex data element uuid
{?sex_measure a nidm:DataElement ;
nidm:isAbout <http://id.nlm.nih.gov/mesh/2018/M0446358> .
}
If the URLs are different between files that could explain why, if this doesn’t not fix your issue, could you paste the contents of your participants.json and male_subj_IDs.sparql file?