Level two, level one...zero? A further investigation to test Jensen's Two-Level Theory of Intelligence.
D000367:Age Factors; D002648:Child; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D007859:Learning Disabilities / Q000523:psychology; D008297:Male; D011582:Psychological Theory; D011610:Psychosocial Deprivation; D012923:Social Class; D012959:Socioeconomic Factors