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Table 2 Sample size, descriptive statistics, and phenotypic correlations

From: A longitudinal twin study of the association between childhood autistic traits and psychotic experiences in adolescence

Sample sizes

Age

N families contacted

MZM

DZM

MZF

DZF

DZOS

8 years

13,941

858

804

1046

874

1659

12 years

8438

814

775

1050

895

1601

14 years

11,118

529

463

662

548

911

16 years

10,874

738

686

1043

905

1560

Measure descriptive statistics

Measure

Cronbach’s α

Possible range of scores

\( \overline{x} \) (SD)

Skew

CAST age 8

0.71

0–31

4.85 (3.09)

0.99 (−0.64)

CAST age 12

0.73

0–30

4.62 (3.15)

1.24 (−0.48)

AQ age 14

0.80

0–87

36.78 (12.16)

0.24 (0.21)

AQ age 16

0.80

0–80

24.04 (10.62)

0.39 (0.36)

SPEQ paranoia

0.93

0–72

12.17 (10.62)

1.56 (−0.61)

SPEQ hallucinations

0.88

0–45

4.66 (6.01)

2.08 (0.22)

SPEQ cognitive disorganisation

0.77

0–11

3.96 (2.85)

0.44 (−0.63)

SPEQ grandiosity

0.86

0–24

5.32 (4.43)

1.19 (−0.41)

SPEQ anhedonia

0.78

0–50

16.36 (7.93)

1.14 (0.17)

SPEQ negative symptoms

0.86

0–27

2.63 (3.63)

2.32 (0.45)

Phenotypic correlations

 

Autistic traits age 8

Autistic traits age 12

Autistic traits age 14

Autistic traits age 16

Paranoia

.02 (ns)

.06*

.07**

.10**

Hallucinations

.07**

.10**

.13**

.14**

Cognitive disorganisation

.08**

.12**

.17**

.21**

Grandiosity

.04*

.08**

.04 (ns)

.00 (ns)

Anhedonia

.14**

.18**

.24**

.30**

Negative symptoms

.27**

.32**

.40**

.47**

  1. All means are given for untransformed scores; skew values are shown for the untransformed measures, and then the standardised residuals used in analyses in parentheses. All Ns are number of twin pairs with data available at each age
  2. SPEQ Specific Psychotic Experiences Questionnaire, CAST Childhood Autism Spectrum Test, AQ Autism Spectrum Quotient, ns nonsignificant
  3. *p < .05; **p < .01
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Molecular Autism

ISSN: 2040-2392