TABLE 2.
Mean raw scores (SD) for the 12-weeks Early Literacy Intervention group and the Control Group for the control measures pre-intervention (t1), immediately post-intervention (t2), and at delayed follow-up (t3, with effect sizes) for the entire sample (N = 189) and the subgroup of children with low oral language skills (n = 63).
| Entire sample (N = 189) | Subgroups low oral language (n = 63) | ||||||||||
| Reliability |
Intervention group (n = 89) |
Control group (n = 100) |
Effect size |
Intervention group (n = 31) |
Control group (n = 32) |
Effect size | |||||
| M | SD | M | SD | M | SD | M | SD | ||||
| Age (months) | |||||||||||
| • t1 | 67.85 | 3.60 | 68.27 | 3.99 | 67.07 | 3.87 | 67.66 | 3.93 | |||
| • t2 | 74.09 | 3.44 | 75.06 | 3.90 | 73.37 | 3.72 | 74.56 | 3.89 | |||
| • t3 | 81.31 | 4.25 | 82.35 | 3.99 | 81.14 | 3.79 | 81.92 | 3.88 | |||
| Early decoding | |||||||||||
| • t1 (12) | 0.95 | 0.27F | 1.38 | 0.74F | 2.33 | 0.10F | 0.59 | 0.06F | 0.35 | ||
| Vocabulary Luxembourgish (CLT) | |||||||||||
| • t1 (40) | 0.79 | 33.10 | 4.49 | 33.94 | 4.48 | −0.192 | 28.23 | 3.80 | 28.75 | 3.39 | −0.142 |
| Vocabulary Luxembourgish (PPVT) | |||||||||||
| • t1 (40) | 0.86 | 29.15 | 6.44 | 29.15 | 6.40 | 0.002 | 22.13 | 4.72 | 21.78 | 3.81 | 0.082 |
| • t2 (40) | 0.82 | 31.56 | 5.04 | 31.22 | 5.44 | 0.072 | 26.60 | 3.77 | 25.44 | 4.17 | 0.292 |
| • t3 (40) | 0.79 | 33.20 | 4.27 | 33.89 | 4.23 | −0.192 | 28.71 | 3.40 | 29.32 | 3.65 | −0.172 |
| Vocabulary German (PPVT) | |||||||||||
| • t3 (228) | 0.98 | 94.91 | 27.33 | 104.99 | 29.20 | −0.362 | 73.93 | 14.29 | 76.24 | 18.13 | −0.232 |
| Early numerical competency | |||||||||||
| • t1 (16) | 0.93 | 2.79 | 3.13 | 3.55 | 4.05 | −0.202 | 1.45F | 1.15 | 1.53F | 1.52 | −0.062 |
| • t2 (16) | 0.94 | 4.53 | 4.26 | 5.93 | 4.88 | −0.181 | 2.83 | 2.91 | 3.53 | 3.46 | −0.191 |
| Non-verbal reasoning (WPPSI) | |||||||||||
| • t1 (29) | 0.80 | 14.78 | 3.63 | 14.43 | 4.65 | 0.112 | 13.61 | 3.60 | 12.03 | 4.47 | 0.392 |
(), maximum possible raw score; CLT, Cross Linguistic Lexical Tasks; PPVT, Peabody Picture Vocabulary Test; F, floor effect. Cohen’s d: 1 = difference in progress between groups divided by pooled initial SD; 2 = difference in means at pre-test/post-test/follow-up divided by pooled SD at pre-test/post-test/follow-up (pre-test scores were at floor/not available for same measure so could not be used). A positive effect (Cohen’s d) means that the Intervention Group did better, whereas a negative effect means results in favor of the Control Group. Reliability coefficient = Cronbach’s alpha.