Table 4. Coefficient of correlation between changes in the COS and other variables under study.
* p-values less than 0.05 are statistically significant; r: Pearson correlation coefficient for continuous variables; rpb: point-biserial correlation coefficient for binary variables; rs: Spearman correlation for ordinal variables
ANB (°): difference between SNA and SNB; CG: condylar guidance in degrees; COS: curve of Spee in mm; FMA (°): Frankfurt horizontal-mandibular plane angle; ICW (mm): intercanine width in lower arch; IMW (mm): intermolar width in lower arch; L1-MP (mm): lower incisor-mandibular plane distance; L1-MP (°): lower incisal inclination to mandibular plane in degrees; L6-MP (mm): lower first molar-mandibular plane distance; L6-MP (°): lower first molar-mandibular plane angle; OB: overbite in mm; OJ: overjet in mm; OP-MP (°): occlusal plane-mandibular plane angle; PM-MP (mm): premolar (first)-mandibular plane distance; SNA (°): angle sella point A in degrees; SNB (°): angle sella point B in degrees; SN-OP (°): sella-nasion plane-occlusal plane angle; U1-PP (mm): upper incisor-palatal plane distance; U1-SN (°): upper incisor-mandibular plane angle; U6-PP (mm): upper first molar-palatal plane distance; WALA-M: William Andrews Larry Andrews point lower first molar; WALA-PM: Willy Andrews Larry Andrews point lower first premolar
| Variable | Correlation coefficient | p-value significance (two-tailed) | |
| Dependent variable | COS | 1 | |
| Categorical variables | Gender rpb (binominal variable) (reference: female/male) | 0.01 | 0.95 |
| Growth pattern rs (ordinal variable) (reference: horizontal/average/vertical) | -0.12 | 0.53 | |
| Alignment rpb (binominal variable) (reference: crowding/spacing) | 0.24 | 0.21 | |
| Continuous variables r | SNA (o) | -0.05 | 0.8 |
| SNB (o) | -0.22 | 0.25 | |
| FMA (o) | 0.22 | 0.26 | |
| SN-OP (o) | 0.07 | 0.7 | |
| Op-MP (o) | 0.23 | 0.24 | |
| CG (o) | 0.05 | 0.8 | |
| LI-MP (o) | -0.36 | 0.06 | |
| UI-SN (o) | -0.08 | 0.67 | |
| L6-MP (o) | 0.07 | 0.73 | |
| L6-MP (mm) | -0.27 | 0.15 | |
| LI-MP (mm) | 0.02 | 0.92 | |
| U6-pal (mm) | -0.2 | 0.33 | |
| UI-pp (mm) | -0.07 | 0.73 | |
| PM-MP (mm) | 0.12 | 0.53 | |
| ICW (mm) | 0.01 | 0.96 | |
| IMW (mm) | 0.1 | 0.6 | |
| WALA-M (mm) | 0.4 | 0.03* | |
| WALA-PM (mm) | 0.17 | 0.38 | |
| OJ (mm) | 0.39 | 0.038* | |
| OB (mm) | 0.57 | 0.002* | |