**5.2.1 Participants**

The study population comprised 474 families and their children attending preschools in the city of Braunschweig (Germany), a moderately sized city with 250,000 inhabitants. Families were recruited for universal and selective prevention efficacy studies of child behaviour problems. Study details for recruitment were described by Hahlweg et al. (2010) and Heinrichs (2006). Data reported here were collected at the first (pre) assessment point. The age of the parents ranged between 23 and 47 years (mothers: *M* = 34.5, *SD* = 5.3; fathers: *M* = 36.4, *SD* = 6.1). The families had between one and four children (*M* = 2.0, *SD* = 0.9). The average age of the target children was 4.5 years (*SD* = 1.0), and 53% (*n* = 253) were boys. Seventy-eight percent (*n* = 219) of the couples were married, and 27 % (*n* = 127) were single parents. 200 fathers (91 % participation rate) completed the questionnaire assessment at pre-test. Forty-two percent of mothers (51 % of fathers) had a higher-track school school leaving qualification (= 13 years of schooling), and 37 % (22 %) had completed medium-track school (= 10 years of schooling). The net family income was equivalent to the German average; 35 % of the families were receiving social security benefits, and 7 % of mothers (5 % of fathers) were immigrants.

### **5.2.2 Measures**

To assess psychopathology in children the German translation of the ASEBA Preschool Forms & Profiles (Achenbach & Rescorla, 2000) was used. The CBCL/1½-5 and the C-TRF are similarly constructed to cover an empirical range of behavioural, emotional and social function problems. Both forms comprise 99 items, and the respondent is requested to rate each item, based on the preceding two months, as 0 for *not true*, 1 for *somewhat or sometimes true* or 2 for *very true or often true*. The CBCL/1½-5 was completed by the mothers and fathers, whereas the kindergarten teachers completed the C-TRF.

The CBCL/1½-5 consists of three problem scales (Internalizing, Externalizing, and Total Problems) and seven syndrome subscales (Emotionally Reactive, Anxious/Depressed, Somatic Complaints, Withdrawn, Sleep Problems, Attention Problems, and Aggressive Behavior). The C-TRF consists also of three problem scales (Internalizing, Externalizing, and Total Problems) and six syndrome subscales (Emotionally Reactive, Anxious/Depressed, Somatic Complaints, Withdrawn, Attention Problems, and Aggressive Behavior). Studies on the German versions of the ASEBA Preschool Forms have supported the psychometric properties, showing good reliability and validity in both clinical and non-clinical populations (e.g. Plück et al., under review). Since there are no German norms available for the ASEBA Preschool Forms & Profiles, we used the norms provided by Achenbach and Rescorla (2000).

#### **5.2.3 Statistical analysis**

Prevalence rates of problem scales and syndrome subscales were calculated for mothers, fathers and caregivers based on the norms provided by Achenbach and Rescorla (2000). Prevalence rates were calculated as a proportion of children with *subclinical* behaviour (T = 60 - 63 for problem scales, T = 65 - 69 for syndrome subscales) and *clinically relevant* behaviour (T ≥ 64 for problem scales, T ≥ 70 for syndrome subscales). Associations between problem scale prevalence and demographic and socio-economic factors (e.g. child´s age and gender, single parenthood, parents' education, family income, migration status) were carried out with Chi square statistics, and the significance level was set at *p* < .01. To determine whether children who had deviant problem scores (T ≥ 60) were at higher risk of having a demographic (economic) factor, odds ratios (OR) and 95 % confidence intervals were calculated.
