| Pretest | Inter-vention group, n = 24 | Waiting group, n = 23 | LN group, n = 36 | ANOVA | Comparison of intervention and waiting groups | Comparison of intervention and LN groups | Comparison of waiting and LN groups | ||||
| Mean (SD) | Mean (SD) | Mean (SD) | F value¶ | p Value | t Score** | p Value | t Score | p Value | t Score | p Value | |
| Assessment of language abilities | |||||||||||
| ELFRA-2 (parent report)* | |||||||||||
| Age in months | 23.9 (1.0) | 24.5 (0.8) | 24.2 (0.7) | F(2,80) = 2.9 | 0.062 | −2.2 | 0.034 | −1.5 | 0.155 | 1.1 | 0.263 |
| Vocabulary | 16.6 (8.9) | 14.3 (9.9) | 160.9 (44.2) | F(2,80) = 238.9 | <0.001 | 0.8 | 0.404 | −19.0 | <0.001 | −19.2 | <0.001 |
| Syntax | 1.0 (2.0) | 1.0 (2.1) | 24.9 (9.1) | F(2,80) = 150.3 | <0.001 | −0.1 | 0.942 | −15.2 | <0.001 | −15.1 | <0.001 |
| Morphology | 0 (0) | 0 (0) | 8.0 (3.8) | F(2,80) = 104.5 | <0.001 | − | – | −12.7 | <0.001 | −12.7 | <0.001 |
| SETK-2† | |||||||||||
| Age in months | 24.5 (0.9) | 24.9 (0.9) | 24.6 (0.8) | F(2,80) = 1.3 | 0.277 | −1.5 | 0.130 | −0.9 | 0.395 | 0.9 | 0.369 |
| Comprehension‡ | |||||||||||
| Words | 52.2 (8.8) | 50.9 (5.6) | 56.3 (7.2) | F(2,80) = 4.6 | 0.015 | 0.6 | 0.561 | −1.9 | 0.064 | −3.2 | 0.002 |
| Sentences | 51.0 (7.9) | 49.0 (7.5) | 58.4 (10.4) | F(2,80) = 9.2 | <0.001 | 0.9 | 0.390 | −3.1 | 0.003 | −4.0 | <0.001 |
| Production‡ | |||||||||||
| Words | 31.1 (2.7) | 30.7 (3.8) | 57.4 (8.8) | F(2,80) = 177.0 | <0.001 | 0.5 | 0.657 | −16.6 | <0.001 | −16.0 | <0.001 |
| Sentences | 37.2 (2.9) | 35.9 (4.1) | 55.0 (7.4) | F(2,80) = 113.9 | <0.001 | 1.3 | 0.218 | −13.1 | <0.001 | −12.8 | <0.001 |
| Assessment of cognitive abilities | |||||||||||
| BSID-II-NL§ | |||||||||||
| MDI | 96.2 (6.9) | 95.3 (8.1) | 114.3 (10.5) | F(2,80) = 43.7 | <0.001 | 0.4 | 0.714 | −8.0 | <0.001 | −7.8 | <0.001 |
| Non-verbal MDI | 115.2 (10.1) | 109.6 (12.6) | 116.5 (10.5) | F(2,80) = 2.9 | 0.063 | 1.7 | 0.101 | −0.5 | 0.64 | −2.2 | 0.034 |
*Raw score; †SETK-2, for description of this language test see Buschmann et al3; ‡t score normative means are 50 (SD 10); §standard score normative means are 100 (SD 15); ¶ANOVA over all three groups; **two sided t test adjusted for multiple testing using Bonferroni corrections.
BSID-II-NL, Bayley Scales of Infant Development, 2nd edn, Netherlands version; ELFRA-2, [Parent report screening questionnaire for early identification of children at risk]; LN, language-normal; MDI, mental developmental index; SETK-2, [Developmental language test for 2-year-old children].