. 2005 Sep 15;32(1):179–194. doi: 10.1093/schbul/sbi048

Table 2.

Study Design Characteristics and Associated Mean (+ SD) Effect Sizes

Design characteristic	n of Studies (%)	n of Effect Sizes	Mean Effect Size (SD)
Diagnostic System for Probands
Research Diagnostic Criteria	7 (12)	37	0.28 (0.35)
Diagnostic and Statistical Manual of Mental Disorders, 3rd ed.	2 (3)	8	0.37 (0.43)
Diagnostic and Statistical Manual of Mental Disorders, 3rd ed.—revised	31 (54)	157	0.38 (0.35)
International Classification of Diseases, 9th revision	1 (2)	1	−0.08 (−)
Diagnostic and Statistical Manual of Mental Disorders, 4th ed.	14 (24)	74	0.45 (0.37)
Operational Criteria for Psychotic Illness	3 (5)	8	0.34 (0.26)
Type of First-Degree Relatives
Siblings	17 (29)	63	0.41 (0.38)
Parents	6 (10)	27	0.45 (0.31)
Offspring	3 (5)	9	0.36 (0.26)
Monozygotic twins	1 (2)	18	0.42 (0.30)
Parents and siblings	11 (19)	69	0.39 (0.35)
Siblings and offspring	1 (2)	20	0.35 (0.23)
Parents, siblings, and offspring	10 (17)	53	0.25 (0.35)
Not reported	9 (16)	26	0.53 (0.47)
Groups Matched on Age
Yes	45 (78)	224	0.36 (0.35)
No	11 (19)	55	0.48 (0.40)
Not reported	2 (3)	6	0.27 (0.28)
Groups Matched on Education
Yes	36 (62)	167	0.34 (0.36)
No	9 (16)	66	0.45 (0.29)
Not reported	13 (22)	52	0.45 (0.41)
Presence of Schizotypal Symptoms^a
Yes	21 (36)	102	0.39 (0.30)
No	20 (35)	120	0.35 (0.36)
Not reported	17 (29)	63	0.43 (0.42)
Asymmetric Inclusion Criteria
Yes	21 (36)	115	0.44 (0.40)
No	30 (52)	134	0.34 (0.32)
Not reported	7 (12)	36	0.36 (0.32)

“Yes” indicates that schizotypy was assessed and elevated rates of symptoms/schizotypal personality diagnoses were reported in the relative group; “no” indicates that schizotypy was assessed and either screened out of the relative group or reported as not significantly elevated compared to controls; “not reported” indicates that no assessment of schizotypy was described.