And the link remained significant even after the researchers controlled for socioeconomic variables, like parental education level and occupation. (parentingscience.com)
The treatment - group and control - group schools were matched on socioeconomic variables, and the student body in both groups of schools had similar ethnic backgrounds. (promisingpractices.net)
They say that this upward trend in loss «can not be explained by commonly - used socioeconomic variables». (climatenewsnetwork.net)